2019 Amazon rainforest wildfires

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2019 Amazon rainforest wildfires
Locations of fires, marked in orange, which were detected by MODIS from August 15 to August 22, 2019
Location	Brazil, Bolivia, Peru, Paraguay
Statistics
Total fires	>40,000
Date(s)	January 2019 — ongoing
Burned area	906,000 hectares (2,240,000 acres)
Cause	Slash-and-burn approach to deforest land for agriculture and effects of climate change due to unusually longer dry season and above average temperatures around worldwide during July and August
Fatalities	2
Map
Amazon rainforest ecoregions as delineated by the WWF in white and the Amazon drainage basin in blue.

The 2019 Amazon rainforest wildfires season saw a year-to-year surge in fires occurring in the Amazon rainforest and Amazon biome within Brazil, Bolivia, Paraguay, and Peru during that year's Amazonian tropical dry season. Fires normally occur around the dry season as slash-and-burn methods are used to clear the forest to make way for agriculture, livestock, logging, and mining, leading to deforestation of the Amazon rainforest. Such activity is generally illegal within these nations, but enforcement of environmental protection can be lax. The increased rates of fire counts in 2019 led to international concern about the fate of the Amazon rainforest, which is the world's largest carbon dioxide sink and plays a significant role in global climate change.

The increased rates were first reported by Brazil's National Institute for Space Research (Instituto Nacional de Pesquisas Espaciais, INPE) in June and July 2019 through satellite monitoring systems, but international attention was drawn to the situation by August 2019 when NASA corroborated INPE's findings, and smoke from the fires, visible from satellite imagery, darkened the city of São Paulo despite being thousands of kilometers from the Amazon. As of August 29, 2019, INPE reported more than 80,000 fires across all of Brazil, a 77% year-to-year increase for the same tracking period, with more than 40,000 in the Brazil's Legal Amazon (Amazônia Legal or BLA), which contains 60% of the Amazon. Similar year-to-year increases in fires were subsequently reported in Bolivia, Paraguay and Peru, with the 2019 fire counts within each nation of over 19,000, 11,000 and 6,700, respectively, as of August 29, 2019. It is estimated that over 906 thousand hectares (2.24×10⁶ acres; 9,060 km²; 3,500 sq mi) of forest within the Amazon biome has been lost to fires in 2019. In addition to the impact on global climate, the fires created environmental concerns from the excess carbon dioxide and carbon monoxide within the fires' emissions, potential impacts on the biodiversity of the Amazon, and threats to indigenous tribes that live within the forest.

The increased rate of fires in Brazil has raised the most concerns as international leaders, particularly French president Emmanuel Macron, and environmental non-government organizations (ENGOs) attributed these to Brazilian president Jair Bolsonaro's pro-business policies that had weakened environmental protections and have encouraged deforestation of the Amazon after he took office in January 2019. Bolsonaro initially remained ambivalent and rejected international calls to take action, asserting that the criticism was sensationalist. Following increased pressure from the international community at the 45th G7 summit and a threat to reject the pending European Union–Mercosur free trade agreement, Bolsonaro dispatched over 44,000 Brazilian troops and allocated funds to fight the fires, and later signed a decree to prevent such fires for a sixty day period.

Other Amazonian countries have been more open for aid and reduce the rate of fires. While Bolivian president Evo Morales was similarly blamed for past policies that encouraged deforestation, Morales has since taken proactive measures to fight the fires and seek aid from other countries. At the G7 summit, Macron negotiated with the other nations to allocate US$22 million for emergency aid to the Amazonian countries affected by the fires.

The Amazon forest and deforestation

There are 670 million ha (1.7 billion acres; 6.7 million km²; 2.6 million sq mi) of Amazon rainforest. Human-driven deforestation of the Amazon rainforest has been a major concern for decades as the rainforest's impact on the global climate has been measured. From a global climate perspective, the Amazon has been the world's largest carbon dioxide sink, and estimated to capture up to 25% of global carbon dioxide generation into plants and other biomass. Without this sink, atmospheric carbon dioxide concentrations would increase and contribute towards higher global temperatures, thus making the viability of the Amazon a global concern. Further, when the forest is lost through fire, additional carbon dioxide is released to the atmosphere, and could potentially contribute significantly to the total carbon dioxide content. The flora also generates significant quantities of water vapor through transpiration which travel large distances to other parts of South America via atmospheric rivers and contribute to the precipitation in these areas. Due to ongoing global climate change, environmental scientists have raised concerns that the Amazon could reach a "tipping point" where it would irreversibly die out, the land becoming more savanna than forest, under certain climate change conditions which are exacerbated by anthropogenic activities.

Human-driven deforestation of the Amazon is used to clear land for agriculture, livestock, and mining, and for its lumber. Most forest is typically cleared using slash-and-burn processes; huge amounts of biomass are removed by first pulling down the trees in the Amazon using bulldozers and giant tractors during the wet season (November through June), followed by torching the tree trunks several months later in the dry season (July through October). Fires are most common in July though August. In some cases, workers performing the burn are unskilled, and may inadvertently allow these fires to spread. While most countries in the Amazon do have laws and environmental enforcement against deforestation, these are not well enforced, and much of the slash-and-burn activity is done illegally.

Deforestation leads to a large number of observed fires across the Amazon during the dry season, usually tracked by satellite data. While it is possible for naturally-occurring wildfires to occur in the Amazon, the chances are far less likely to occur, compared to those in California or in Australia. Even with global warming, spontaneous fires in the Amazon cannot come from warm weather alone, but warm weather is capable of exacerbating the fires once started as there will be drier biomass available for the fire to spread. Alberto Setzer of INPE estimated that 99% of the wildfires in the Amazon basin are a result of human actions, either on purpose or accidentally. Manmade fires in the Amazon also tend to elevate their smoke into the higher atmosphere due to the more intense burn of the dry biomass, compared with naturally occurring wildfires. Further evidence of the fires being caused by human activity is due to their clustering near roads and existing agricultural areas rather than remote parts of the forest.

Fires in Brazil

Past deforestation and fires in Brazil

Location of Amazônia Legal (red) within Brazil

 

States within Amazônia Legal.

Brazil's role in deforestation of the Amazon rainforest has been a significant issue since the 1970s, as 60% of the Amazon is contained within Brazil, designated as the Brazil's Legal Amazon (Amazônia Legal, BLA). Since the 1970s, Brazil has consumed approximately 12 percent of the forest, representing roughly 77.7 million ha (192 million acres)—an area larger than that of the US state of Texas. Most of the deforestation has been for natural resources for the logging industry and land clearing for agricultural and mining use. Forest removal to make way for cattle ranching was the leading cause of deforestation in the Brazilian Amazon from the mid-1960s on. The Amazon region has become the largest cattle ranching territory in the world. According to the World Bank, some 80% of deforested land is used for cattle ranching. Seventy per cent of formerly forested land in the Amazon, and 91% of land deforested since 1970, is used for livestock pasture. According to the Center for International Forestry Research (CIFOR), "between 1990 and 2001 the percentage of Europe's processed meat imports that came from Brazil rose from 40 to 74 percent" and by 2003 "for the first time ever, the growth in Brazilian cattle production, 80 percent of which was in the Amazon[,] was largely export driven." The Brazilian states of Pará, Mato Grosso, and Rondônia, located along the southern border of the Amazon rainforest, are in what is called the "deforestation arc".

Deforestation within Brazil is partially driven by growing demand for beef and soy exports, particularly to China and Hong Kong. Brazil is one of the largest exporters of beef, accounting for more than 20% of global trade of the commodity. Brazil exported over 1.6 million tonnes of beef in 2018, the highest volume in recorded history. Brazil's cattle herd has increased by 56% over the last two decades. Ranchers wait until the dry season to slash-and-burn to give time for the cattle to graze. While slash-and-burn can be controlled, unskilled farmers may end up causing wildfires. Wildfires have increased as the agricultural sector has pushed into the Amazon basin and spurred deforestation. In recent years, "land-grabbers" (grileiros) have been illegally cutting deep into the forest in "Brazil's indigenous territories and other protected forests throughout the Amazon".

Number of fires in Brazil's Amazônia Legal between January 1 and August 26 by year, reported by INPE

 

Past data from INPE has shown the number of fires with the BLA from January to August in any year to be routinely higher than 60,000 fires from 2002 to 2007 and as high as 90,000 in 2003. Fire counts have generally been higher in years of drought (2007 and 2010), which are often coupled with El Niño events.

Within international attention on the protection of the Amazon around the early 2000s, Brazil took a more proactive approach to deforestation of the Amazon rainforest. In 2004, the Brazilian government had established the Federal Action Plan for Prevention and Control of Deforestation in the Amazon (PPCDAM), with the goal to reduce the rate of deforestation through land use regulation, environmental monitoring, and sustainable activities, promoted through partnerships at the federal and private level, and legal penalties for violations. Brazil also invested in more effective measures to fight fires, including fire-fighting airplanes in 2012. By 2014, USAID was teaching the indigenous people how to fight fires. As a result of enforcement of PPCDAM, the rate of deforestation in the Brazilian Amazon dropped 83.5% of their 2004 rates by 2012. However, in 2014, Brazil fell into an economic crisis, and as part of that recovery, pushed heavily on its exports of beef and soy to help bolster its economy, which caused a reversal in the falling deforestation rates. The Brazilian government has been defunding scientific research since the economic crisis.

To support PPCDAM, the INPE began developing systems to monitor the Amazon rainforest. One early effort was the Amazon Deforestation Satellite Monitoring Project (PRODES), which is a highly-detailed satellite imagery-based approach to calculate wildfires and deforestation losses on an annual basis. In 2015, INPE launched five complementary projects as part of the Terra Brasilis project to monitor deforestation closer to real-time. Among these include the Real-Time Deforestation Detection System (DETER) satellite alert system, allowing them to capture incidents of wildfires in 15-day cycles. The daily data is published on the regularly updated Brazilian Environmental Institute government website, and later corroborated with the annual and more accurate PRODES data.

By December 2017, INPE had completed a modernization process and had expanded its system to analyze and share data on forest fires. It launched its new TerraMA2Q platform—software which adapts fire-monitoring data software including the "occurrence of irregular fires". Although the INPE was able to provide regional fire data since 1998, the modernization increased access. Agencies that monitor and fight fires include the Brazilian Federal Environment and Renewable Resources Agency (IBAMA), as well as state authorities. The INPE receives its images daily from 10 foreign satellites, including the Terra and Aqua satellites—part of the NASA's Earth Observation System (EOS). Combined, these systems are able to capture the number of fires on a daily basis, but this number does not directly measure the area of forest lost to these fires; instead, this is done with fortnightly imaging data to compare the current state of the forest with reference data to estimate acreage lost.

Jair Bolsonaro was elected as President of Brazil in October 2018 and took office in January 2019, after which he and his ministries changed governmental policies to weaken protection of the rainforest and make it favorable for farmers to continue practices of slash-and-burn clearing, thus accelerating the deforestation from previous years. Land-grabbers had used Bolsonaro's election to extend their activities into cutting in the land of the previously isolated Apurinã people in Amazonas where the "world's largest standing tracts of unbroken rainforest" are found. Upon entering office, Bolsonaro cut US$23 million from Brazil's environmental enforcement agency, making it difficult for the agency to regulate deforestation efforts. Bolsonaro and his ministers had also segmented the environmental agency, placing part of its control under the agricultural ministry, which is led by the country's farming lobby, weakened protections on natural reserves and territories belonging to indigenous people, and encouraged businesses to file counter-land claims against regions managed by sustainable forestry practices.

2019 Brazil dry season fires

Agricultural fires in southern Pará, Brazil in August 2019.

 

INPE alerted the Brazilian government to larger-than-normal growth in the number of fires through June to August 2019. The first four months of the year were wetter-than-average, discouraging slash-and-burn efforts. However, with the start of the dry season in May 2019, the number of wildfires jumped greatly. Additionally, NOAA reported that, regionally, the temperatures in the January-July 2019 period were the second warmest year-to-date on record.INPE reported a year-to-year increase of 88% in wildfire occurrences in June 2019. There was further increase in the rate of deforestation in July 2019, with the INPE estimating that more than 1,345 square kilometres (519 sq mi; 134,500 ha; 332,000 acres) of land had been deforested in the month and would be on track to surpass the area of Greater London by the end of the month.

The month of August 2019 saw a large growth in the number of observed wildfires according to INPE. By August 11, Amazonas had declared a state of emergency. The state of Acre entered into a environmental alert on August 16. In early August, local farmers in the Amazonian state of Pará placed an ad in the local newspaper calling for a queimada or "Day of Fire" on August 10, 2019, organizing large scale slash-and-burn operations knowing that there was little chance of interference from the government. Shortly after, there was an increase in the number of wildfires in the region.

INPE reported on August 20 that it had detected 39,194 fires in the Amazon rainforest since January. This represented a 77 percent increase in the number of fires from the same time period in 2018. However, the NASA-funded NGO Global Fire Emissions Database (GFED) shows 2018 as an unusually low fire year compared to historic data from 2004–2005 which are years showing nearly double the number of counted fires. INPE had reported that at least 74,155 fires have been detected in all of Brazil, which represents a 84-percent increase from the same period in 2018. NASA originally reported in mid-August that MODIS satellites reported average numbers of fires in the region compared with data from the past 15 years; the numbers were above average for the year in the states of Amazonas and Rondônia, but below average for Mato Grosso and Pará. NASA later clarified that the data set they had evaluated previous was through August 16, 2019. By August 26, 2019, NASA included more recent MODIS imagery to confirm that the number of fires were higher than in previous years.

INPE satellite imagery of a 70-by-70 mile area along the Purus River between Canutama and Lábrea in the state of Amazonas, taken on August 16, 2019, showing several plumes of smoke from wildfires, including areas that have been deforested

 

By August 29, 80,000 fires had broken out in Brazil which represents a 77% rise on the same period in 2018, according to BBC. INPE reported that in the period from January 1 to August 29, across South America, and not exclusive to the Amazon rainforest, there were 84,957 fires in Brazil, 26,573 in Venezuela, 19,265 in Bolivia, 14,363 in Colombia, 14,969 in Argentina, 10,810 in Paraguay, 6,534 in Peru, 2,935 in Chile, 898 in Guyana, 407 in Uruguay, 328 in Ecuador, 162 in Suriname, and 11 in French Guiana.

First media reports

While INPE's data had been reported in international sources earlier, news of the wildfires were not a major news story until around August 20, 2019. On that day, the smoke plume from the fires in Rondônia and Amazonas caused the sky to darken at around 2 p.m. over São Paulo—which is almost 2,800 kilometres (1,700 mi) away from the Amazon basin on the eastern coast. NASA and US National Oceanic and Atmospheric Administration (NOAA) also published satellite imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellitein alignment with INPE's own, that showed smoke plumes from the wildfires were visible from space. INPE and NASA data, along with photographs of the ongoing fires and impacts, caught international attention and became a rising topic on social media, with several world leaders, celebrities, and athletes expressing their concerns.

According to Vox, of all the concurrent wildfires elsewhere in the world, the wildfires in the Amazon rainforest in Brazil were the most "alarming".

Responses of the Brazilian government

In the months prior to August 2019, Bolsonaro mocked international and environmental groups that felt his pro-business actions enabled deforestation. At one point in August 2019, Bolsonaro jokingly calling himself "Captain Chainsaw" while asserting that INPE's data was inaccurate. After INPE announced an 88% increase of wildfires in July 2019, Bolsonaro claimed "the numbers were fake" and fired Ricardo Magnus Osório Galvão, the INPE director. Bolsonaro claimed Galvão was using the data to lead an "anti-Brazil campaign". Bolsonaro had claimed that the fires had been deliberately started by environmental NGOs, although he provided no evidence to back up the accusation. NGOs such as WWF Brasil, Greenpeace, and the Brazilian Institute for Environmental Protection countered Bolsonaro's claims.

Bolsonaro, on August 22, argued that Brazil did not have the resources to fight the fires, as the "Amazon is bigger than Europe, how will you fight criminal fires in such an area?".

Historically, Brazil has been guarded about international intervention into the BLA, as the country sees the forest as a critical part of Brazil's economy. Bolsonaro and his government have continued to speak out against any international oversight of the situation. Bolsaonaro considered French President Emmanuel Macron's comments to have a "sensationalist tone" and accusing him of interfering in what he considers is a local problem. Of Macron and German Chancellor Angela Merkel, Bolsonaro stated: "They still haven't realized that Brazil is under new direction. That there's now a president who is loyal to [the] Brazilian people, who says the Amazon is ours, who says bad Brazilians can't release lying numbers and campaign against Brazil."

Bolsonaro's foreign minister Ernesto Araújo has also condemned the international criticism of Bolsonaro's reaction to the wildfires, calling it "savage and unfair" treatment towards Bolsonaro and Brazil. Araújo stated that: "President Bolsonaro's government is rebuilding Brazil", and that foreign nations were using the "environmental crisis" as a weapon to stop this rebuilding. General Eduardo Villas Bôas, former commander of the Brazilian Army, considered the criticism of world leaders, like Macron and Canadian Prime Minister Justin Trudeau, to be directly challenging "Brazilian sovereignty", and may need to be met with military response.

With increased pressure from the international community, Bolsonaro appeared more willing to take proactive steps against the fires, saying by August 23, 2019, that his government would take a "zero tolerance" approach to environmental crimes. He engaged the Brazilian military to help fight the wildfires on August 24, which Joint Staff member Lt. Brig. Raul Botelho stated was to create a "positive perception" of the government's efforts. Among military support included 43,000 troops as well as four firefighting aircraft, and an allocated US$15.7 million for fire-fighting operations. Initial efforts were principally located in the state of Rondônia, but the Defense Ministry stated they plan to offer support for all seven states affected by the fires. On August 28, Bolsonaro signed a decree banning the setting of fires in Brazil for a period of 60 days, making exceptions for those fires made purposely to maintain environmental forest health, to combat wildfires, and by the indigenous people of Brazil. However, as most fires are set illegally, it is unclear what impact this decree could have.

Rodrigo Maia, president of the Chamber of Deputies, announced that he would form a parliamentary committee to monitor the problem. In addition, he said that the Chamber will hold a general commission in the following days to assess the situation and propose solutions to the government.

After a report from Globo Rural reveal that a WhatsApp group of 70 people was involved with the Day of Fire, Jair Bolsonaro determined the opening of investigations by Federal Police.

Brazil banned clearing land by setting fire to it on 29 August 2019.

More measures taken by the Brazilian government of Jair Bolsonaro to stop the fires include:

• Accepting 4 planes from Chile to battle the fires.
• Accepting 12 million dollars of aid from the United Kingdom government
• Softening his position about aid from the G7.
• Appealing for an international conference to preserve the Amazon with participation of all countries that have some part of the Amazon rainforest in their territory

Protests against Brazilian government policies

In regards to the displacement of the indigenous people, Amnesty International has highlighted the change in protection of lands belonging to the indigenous people, and have called on other nations to pressure Brazil to restore these rights, as they are also essential to protecting the rainforest. Ivaneide Bandeira Cardoso, founder of Kanindé, a Porto Velho-based advocacy group for indigenous communities, said Bolsonaro is directly responsible for the escalation of forest fires throughout the Amazon this year. Cardoso said the wildfires are a "tragedy that affects all of humanity" since the Amazon plays an important role in the global ecosystem as a carbon sink to reduce the effects of climate change.

Thousands of Brazilian citizens held protests in several major cities from August 24, 2019, onward to challenge the government's reaction to the wildfires. Protesters around the world also held events at Brazilian embassies, including in London, Paris, Mexico City, and Geneva.

Protest in Porto Alegre on August 24, 2019

Impact on the indigenous peoples of Brazil

In addition to environmental harm, the slash-and-burn actions leading to the wildfires have threatened the approximately 306,000 indigenous people in Brazil who reside near or within the rainforest. Bolsanaro had spoken out against the need to respect the demarcation of lands for indigenous people established in the 1988 Constitution of Brazil. According to a CBC report on Brazil's wildfires, representatives of the indigenous people have stated that farmers, loggers, and miners, emboldened by the Brazilian government's policies, have forced these people out of their lands, sometimes through violent means, and equated their methods with genocide. Some of these tribes have vowed to fight back against those engaged in deforestation to protect their lands.

International responses

Several international governments and environmental groups raised concerns at Bolsonaro's stance on the rainforest and the lack of attempts by his government to slow the wildfires. Among the most vocal was Macron, given the proximity of French Guiana to Brazil. Macron called the Amazon wildfires an "international crisis", while claiming the rainforest produces "20% of the world's oxygen"—a statement disputed by academics. He said, "Our house is burning. Literally."

Discussion about the fires came into the final negotiations of the EU–Mercosur Free Trade Agreement between the EU and Mercosur, a trade bloc of Argentina, Brazil, Uruguay, and Paraguay. With the wildfires on-going, both Macron and Irish Prime Minister Leo Varadkar have stated they will refuse to ratify the trade deal unless Brazil commits to protecting the environment.

Finance minister of Finland Mika Lintilä suggested the idea of a EU ban on Brazilian beef imports until the country takes steps to stop the deforestation.

Fires in Bolivia

Background

In Bolivia, the annual seasonal chaqueo has become an "entrenched custom" that is currently encouraged by recent political decisions. The forest fires in Bolivia occurred during the dry season but they happened independently of Brazil's fires.

Bolivia has 7.7 percent of the Amazon rainforest within its borders. The Bolivian Amazon covers 19.402 million hectares (47.94 million acres) which comprise 37.7 percent of Bolivia's forests and 17.7 percent of Bolivia's land mass. Bolivia's forests cover a total of 51.407 million hectares (127.03 million acres), including the Chiquitano dry forests which is part of the Amazon biome and a transition zone between the Amazon rainforest and the drier forests of the southern Chaco region.

Santa Cruz Department

By August 16, Bolivia's Santa Cruz had declared a departmental emergency because of the forest fires. From August 18 to August 23, approximately 800 thousand hectares (2.0 million acres) of the Chiquitano dry forests were destroyed, more than what was lost over a typical two-year period. By August 24, the fires had already destroyed 1,011 thousand hectares (2.50 million acres) of forestland in the Santa Cruz and were burning near Santa Cruz, Bolivia. By August 26, wildfires had destroyed over 728 thousand hectares (1.80 million acres) of Bolivia's savanna and tropical forests, according to the Bolivian Information Agency (BIA). Over a period of five days, from August 18 to August 22, 450 thousand hectares (1.1 million acres) of forest near Roboré were destroyed.

On August 25, 4,000 state employees and volunteers were fighting the fires. By August 25, the Chiquitano has lost 650 thousand hectares (1.6 million acres) of tropical forest within both the Amazon and the dry forests, mostly within the Santa Cruz province; like the Brazil fires, such fires occur during the dry season, but the number of fires in 2019 were larger than in previous years. Throughout August, wildfires have been spreading across four states. Jaguars, tapirs, and dozens of endangered species are threatened. By August 26, fires in the Dionisio Foianini Triangle—the Brazil-Bolivia-Paraguay triangle had destroyed savannah and tropical forest "near Bolivia's border with Paraguay and Brazil".

President Evo Morales initially ignored the fires. Juan Quintana, the president's chief of staff, had said they did not require "foreign firefighting aid". In the week of August 18, Morales dispatched soldiers and three helicopters to fight fires in an area about the size of Oregon. On August 22, Morales contracted the Colorado-based Boeing 747 Supertanker (also known as Global SuperTanker) to conduct firefighting missions over the Bolivian Amazon, after having previously refused to call on external help. The 747 Supertanker is the largest firefighting aircraft in the world, which can hold approximately 19,000 gallons of water per trip. Morales has stated that the governments of Spain, Chile, and Paraguay have reached out to him to provide help for fighting the fires.

The government had been trying to determine the cause of the fires, with the Bolivian land management authority attributing 87% of the fires to illegal slash-and-burn by farmers. Multiple NGOs assert that deforestation rates in Bolivia increased 200 percent after the government quadrupled available land for deforestation to farmers in 2015. The land authority attributed the increase on lax environmental enforcement.

Political opponents of Morales alleged that the Supreme Decree 3973, a mandate to further beef production in the Amazon region, is a major cause of the Bolivian fires. The Santa Cruz province is a critical area for agriculture and cattle-rearing.

Probioma's Miguel Crespo said that, "It may take up to 200 years for the forests in Bolivia to heal. I've never seen an environmental tragedy on this scale ...The government has detonated an environmental disaster. In large part, this tragedy is the result of the state's populism and development vision based on agribusiness."

Fires in Paraguay's Pantanal

By August 22, fire emergencies in Paraguay's Alto Paraguay district and the UNESCO protected Pantanal region were issued by its federal government. Paraguay President Mario Abdo Benítez was in close contact with Bolivia's Morales to coordinate response efforts. By August 17, as wind direction changed, flames from fires in Bolivia began to enter northern Paraguay's Three Giants natural reserve in the Paraguayan Pantanal natural region. By August 24, when the situation had stabilized, Paraguay had lost 39,000 hectares (96,000 acres) in the Pantanal. An Universidad Nacional de Asunción representative lamented the disaster failed to attract as much media attention as the fires in the Amazon rainforest.

While most of the Pantanal regions—140,000 and 195,000 square kilometres (54,000 and 75,000 sq mi)—is within Brazil's borders in the state of Mato Grosso do Sul, the natural region also extends into Mato Grosso and portions of Bolivia. It sprawls over an area estimated at between 140,000 and 195,000 square kilometres (54,000 and 75,000 sq mi). Within the Pantanal natural region, which is located between Brazil and Bolivia, is the "world's largest tropical wetland area". According one of the engineers charged with monitoring satellite data showing the "evolution of the fires", the Pantanal is a "complex, fragile, and high-risk ecosystem because it's being transformed from a wetland to a productive system". The Pantana is bounded by the Humid Chaco to the south, the Arid Chaco dry forests to the southwest, Cerrado savannas lie to the north, east and southeast, and the Chiquitano dry forests, to the west and northwest, where thousands of hectares burned in Bolivia. 

A national parks researcher said that outsiders only know the Amazon, which is a "shame because the Pantanal is a very important ecological place". The Paraná River, which flows through Argentina, Brazil and Paraguay, is the "second largest river system in South America".

Fires in Peru

Peru had nearly twice the growth in the number of fires in 2019 than Brazil, with most believed to be illegally set by ranchers, miners, and coca growers. Much of the fires are in the Madre de Dios which borders Brazil and Bolivia, though the fires there are not a result of those started in the other countries, according to the regional authority. However, they are still concerned about the impact of downwind emissions, particularly carbon monoxide, on residents of Madre de Dios. There were 128 forest fires reported in Peru in August 2019.

Environmental impacts of the fires

Emissions

Images created by the Atmospheric Infrared Sounder which depict carbon monoxide caused by fires in the Amazon region of Brazil from Aug. 8-22, 2019.

 

Locations of active wildfires (marked in orange) in the Amazon as of 22 August 2019

 

By August 22, NASA's AIRS published maps of increased carbon monoxide and carbon dioxide resulting from Brazil's wildfires. On the same day, the European Union's Copernicus Climate Change Service reported a "discernible spike" in emissions of carbon monoxide and carbon dioxide generated by the fires.

Areas downwind of the fires have become covered with smoke, which can potentially last upwards of months at a time if the fires are left to burn out. Hospitals in cities like Porto Velho had reported over three times the average number of cases of patients suffering from the effects of smoke over the same year-to-year period in August 2019 than in other previous years. Besides hindering breathing, the smoke can exacerbates patients with asthma or bronchitis and have potential cancer risk, generally affecting the youth and elderly the most.

Biodiversity

Scientists at the Natural History Museum in London, described how while some forests have adapted to fire as "important part of a forest ecosystem's natural cycle", the Amazon rainforest—which is "made up of lowland, wetland forests"—is "not well-equipped to deal with fire". Other Amazon basin ecosystems, like the Cerrado region, with its "large savannah, and lots of plants there have thick, corky, fire resistant stems", is "fire adapted".

Mazeika Sullivan, associate professor at Ohio State University's School of Environment and Natural Resources, explained that the fires could have a massive toll on wildlife in the short term as many animals in the Amazon are not adapted for extraordinary fires. Sloths, lizards, anteaters, and frogs may unfortunately perish in larger numbers than others due to their small size and lack of mobility. Endemic species, like Milton's titi and Mura's saddleback tamarin, are believed to be beset by the fires. Aquatic species could also be affected due to the fires changing the water chemistry into a state unsuitable for life. Long-term effects could be more catastrophic. Parts of the Amazon rainforest's dense canopy were destroyed by the fires therefore exposing the lower levels of the ecosystem, which then alters the energy flow of the food chain.

International actions

On August 22, the Bishops Conference for Latin America called the fires a "tragedy" and urged the UN, the international community, and governments of Amazonian countries, to "take serious measures to save the world's lungs". Colombian President Ivan Duque stated he wanted to lead a conservation pact with the other nations that share the Amazon rainforest with plans to present this to the UN General Assembly. Duque said, "We must understand the protection of our Mother Earth and our Amazon is a duty, a moral duty."

United Nations Secretary General António Guterres stated on August 23, that: "In the midst of the global climate crisis, we cannot afford more damage to a major source of oxygen and biodiversity."

G7 Summit and emergency aid

Attention to the wildfires increased in the week prior to the G7 summit discussions on August 24–26 in Biarritz, France, led by President Macron. Macron stated his intent to open discussions related to the wildfires in the Brazilian part of the Amazon and Bolsonaro's response to them. Merkel has also backed Macron's statements and planned to make the issue a part of the G7 discussions; via a spokesperson, Merkel stated: "The extent of the fires in the Amazon area is shocking and threatening, not only for Brazil and the other affected countries, but also for the whole world." Macron further stated that possible international statute to protect the rainforest may be needed "if a sovereign state took concrete actions that clearly went against the interest of the planet". Bolsonaro expressed concern to United States president Donald Trump, that with Brazil not part of the G7, the country would be unrepresented in any such debate. Trump offered to take the position of the Brazilian government to the meeting and said that the US government did not agree to discuss the issue without Brazil's presence. Trump himself was absent from the environmental portion of the summit held on August 26, 2019, that discussed the fires and climate change, though members of his advisory team were in attendance.

During the summit, Macron and Chilean president Sebastián Piñera negotiated with the other nations to authorize US$22 million in emergency funding to Amazonian countries to help fight the fires. The Trump administration did not approve of the measure as the funding set certain requirements on its use. When the final negotiations were completed, Bolsonaro stated that he would refuse those funds for Brazil, claiming that Macron's interests were about protecting France's agricultural business in French Guiana from Brazil's competition. Bolsonaro also criticised Macron by comparing the Amazon fires to the Notre-Dame de Paris fire earlier in 2019, suggesting Macron should take care of their internal fires before reaching out internationally. The governors of the states of Brazil most affected by the fires pressured Bolsonaro to accept the aid given. Bolsonaro later clarified that he would accept foreign aid for the fires, but only if Brazil has the authority to determine how it is used.

Amazon country summit

Brazil's Bolsonaro stated on August 28, 2019, that the countries sharing the Amazon rainforest, excluding Venezuela, will hold a summit in Colombia on September 6, 2019, to discuss the ongoing Amazon fire situation.

2019 wildfires in the media

The media coverage had also broadly overshadowed the Amazon fires in Bolivia, Peru, and Paraguay by the fires and international impact of those in the BLA. The Amazon wildfires also occurred shortly after major wildfires reported in Greenland and Siberia after a globally hotter-than-average June and July, drawing away coverage of these natural disasters.

Some of these photographs shared on social media were from past fire events in the Amazon or from fires elsewhere. Agence France-Presse and El Comercio published guides to help people "fact-check" on misleading photos.

Celebrity responses to Amazon wildfires

American actor Leonardo DiCaprio said his environmental organization Earth Alliance is donating $5 million to local groups and indigenous communities to help protect the Amazon.

Other celebrities who made public contributions include actresses Vanessa Hudgens and Lana Condor, and Japanese musician Yoshiki.

On August 26, 2019, Europe's richest man, Bernard Arnault, declared that his LVMH group will donate $11 million to aid in the fight against the Amazon rainforest wildfires.

American restaurateur Eddie Huang said he is going vegan as a result of the 2019 Amazon fires. Khloé Kardashian urged her 98 million Instagram followers to adopt a plant-based diet for the same reason.

Nanoinformatics

From Wikipedia, the free encyclopedia

 

Nanoinformatics is the application of informatics to nanotechnology. It is an interdisciplinary field that develops methods and software tools for understanding nanomaterials, their properties, and their interactions with biological entities, and using that information more efficiently. It differs from cheminformatics in that nanomaterials usually involve nonuniform collections of particles that have distributions of physical properties that must be specified. The nanoinformatics infrastructure includes ontologies for nanomaterials, file formats, and data repositories.

Nanoinformatics has applications for improving workflows in fundamental research, manufacturing, and environmental health, allowing the use of high-throughput data-driven methods to analyze broad sets of experimental results. Nanomedicine applications include analysis of nanoparticle-based pharmaceuticals for structure–activity relationships in a similar manner to bioinformatics.

Background

Context of nanoinformatics as a convergence of science and practice at the nexus of safety, health, well-being, and productivity; risk management; and emerging nanotechnology.

 

While conventional chemicals are specified by their chemical composition, and concentration, nanoparticles have other physical properties that must be measured for a complete description, such as size, shape, surface properties, crystallinity, and dispersion state. In addition, preparations of nanoparticles are often non-uniform, having distributions of these properties that must also be specified. These molecular-scale properties influence their macroscopic chemical and physical properties, as well as their biological effects. They are important in both the experimental characterization of nanoparticles and their representation in an informatics system. The context of nanoinformatics is that effective development and implementation of potential applications of nanotechnology requires the harnessing of information at the intersection of safety, health, well-being, and productivity; risk management; and emerging nanotechnology.

A graphical representation of a working definition of nanoinformatics as a life-cycle process

 

One working definition of nanoinformatics developed through the community-based Nanoinformatics 2020 Roadmap and subsequently expanded is:

• Determining which information is relevant to meeting the safety, health, well-being, and productivity objectives of the nanoscale science, engineering, and technology community;
• Developing and implementing effective mechanisms for collecting, validating, storing, sharing, analyzing, modeling, and applying the information;
• Confirming that appropriate decisions were made and that desired mission outcomes were achieved as a result of that information; and finally
• Conveying experience to the broader community, contributing to generalized knowledge, and updating standards and training.

Data representations

Although nanotechnology is the subject of significant experimentation, much of the data are not stored in standardized formats or broadly accessible. Nanoinformatics initiatives seek to coordinate developments of data standards and informatics methods.

Ontologies

An overview of the eNanoMapper nanomaterial ontology

 

In the context of information science, an ontology is a formal representation of knowledge within a domain, using hierarchies of terms including their definitions, attributes, and relations. Ontologies provide a common terminology in a machine-readable framework that facilitates sharing and discovery of data. Having an established ontology for nanoparticles is important for cancer nanomedicine due to the need of researchers to search, access, and analyze large amounts of data.

The NanoParticle Ontology is an ontology for the preparation, chemical composition, and characterization of nanomaterials involved in cancer research. It uses the Basic Formal Ontology framework and is implemented in the Web Ontology Language. It is hosted by the National Center for Biomedical Ontology and maintained on GitHub. The eNanoMapper Ontology is more recent and reuses wherever possible already existing domain ontologies. As such, it reuses and extends the NanoParticle Ontology, but also the BioAssay Ontology, Experimental Factor Ontology, Unit Ontology, and ChEBI.

File formats

Flowchart depicting the ways to identify different components of a material sample to guide the creation of an ISA-TAB-Nano Material file

 

ISA-TAB-Nano is a set of four spreadsheet-based file formats for representing and sharing nanomaterial data, based on the ISA-TAB metadata standard. In Europe, other templates have been adopted that were developed by the Institute of Occupational Medicine, and by the Joint Research Centre for the NANoREG project.

Tools

Nanoinformatics is not limited to aggregating and sharing information about nanotechnologies, but has many complementary tools, some originating from chemoinformatics and bioinformatics.

Databases and repositories

Over the last couple of years, various databases have been made available.

caNanoLab, developed by the U.S. National Cancer Institute, focuses on nanotechnologies related to biomedicine. The NanoMaterials Registry, maintained by RTI International, is a curated database of nanomaterials, and includes data from caNanoLab.

The eNanoMapper database, a project of the EU NanoSafety Cluster, is a deployment of the database software developed in the eNanoMapper project. It has since been used in other settings, such as the EU Observatory for NanoMaterials (EUON).

Other databases include the Center for the Environmental Implications of NanoTechnology's NanoInformatics Knowledge Commons (NIKC) and NanoDatabank, PEROSH's Nano Exposure & Contextual Information Database (NECID), Data and Knowledge on Nanomaterials (DaNa), and Springer Nature's Nano database.

Applications

Nanoinformatics has applications for improving workflows in fundamental research, manufacturing, and environmental health, allowing the use of high-throughput data-driven methods to analyze broad sets of experimental results.

Nanoinformatics is especially useful in nanoparticle-based cancer diagnostics and therapeutics. They are very diverse in nature due to the combinatorially large numbers of chemical and physical modifications that can be made to them, which can cause drastic changes in their functional properties. This leads to a combinatorial complexity that far exceeds, for example, genomic data. Nanoinformatics can enable structure–activity relationship modelling for nanoparticle-based drugs. Nanoinformatics and biomolecular nanomodeling provide a route for effective cancer treatment. Nanoinformatics also enables a data-driven approach to the design of materials to meet health and environmental needs.

Modeling and NanoQSAR

Viewed as a workflow process, nanoinformatics deconstructs experimental studies using data, metadata, controlled vocabularies and ontologies to populate databases so that trends, regularities and theories will be uncovered for use as predictive computational tools. Models are involved at each stage, some material (experiments, reference materials, model organisms) and some abstract (ontology, mathematical formulae), and all intended as a representation of the target system. Models can be used in experimental design, may substitute for experiment or may simulate how a complex system changes over time.

At present, nanoinformatics is an extension of bioinformatics due to the great opportunities for nanotechnology in medical applications, as well as to the importance of regulatory approvals to product commercialization. In these cases, the models target, their purposes, may be physico-chemical, estimating a property based on structure (quantitative structure–property relationship, QSPR); or biological, predicting biological activity based on molecular structure (quantitative structure–activity relationship, QSAR) or the time-course development of a simulation (physiologically based toxicokinetics, PBTK). Each of these has been explored for small molecule drug development with a supporting body of literature. 

Particles differ from molecular entities, especially in having surfaces that challenge nomenclature system and QSAR/PBTK model development. For example, particles do not exhibit an octanol–water partition coefficient, which acts as a motive force in QSAR/PBTK models; and they may dissolve in vivo or have band gaps. Illustrative of current QSAR and PBTK models are those of Puzyn et al. and Bachler et al. The OECD has codified regulatory acceptance criteria, and there are guidance roadmaps with supporting workshops to coordinate international efforts.

Communities

Communities active in nanoinformatics include the European Union NanoSafety Cluster, The U.S. National Cancer Institute National Cancer Informatics Program's Nanotechnology Working Group, and the US–EU Nanotechnology Communities of Research.

Nanoinformatics roles, responsibilities, and communication interfaces

 

Individuals who engage in nanoinformatics can be viewed as fitting across four categories of roles and responsibilities for nanoinformatics methods and data:

• Customers, who need either the methods to create the data, the data itself, or both, and who specify the scientific applications and characterization methods and data needs for their intended purposes;
• Creators, who develop relevant and reliable methods and data to meet the needs of customers in the nanotechnology community;
• Curators, who maintain and ensure the quality of the methods and associated data; and
• Analysts, who develop and apply methods and models for data analysis and interpretation that are consistent with the quality and quantity of the data and that meet customers’ needs.

In some instances, the same individuals perform all four roles. More often, many individuals must interact, with their roles and responsibilities extending over significant distances, organizations, and time. Effective communication is important across each of the twelve links (in both directions across each of the six pairwise interactions) that exist among the various customers, creators, curators, and analysts.

History

One of the first mentions of nanoinformatics was in the context of handling information about nanotechnology.

An early international workshop with substantial discussion of the need for sharing all types of information on nanotechnology and nanomaterials was the First International Symposium on Occupational Health Implications of Nanomaterials held 12–14 October 2004 at the Palace Hotel, Buxton, Derbyshire, UK. The workshop report included a presentation on Information Management for Nanotechnology Safety and Health that described the development of a Nanoparticle Information Library (NIL) and noted that efforts to ensure the health and safety of nanotechnology workers and members of the public could be substantially enhanced by a coordinated approach to information management. The NIL subsequently served as an example for web-based sharing of characterization data for nanomaterials.

The National Cancer Institute prepared in 2009 a rough vision of, what was then still called, nanotechnology informatics, outlining various aspects of what nanoinformatics should comprise. This was later followed by two roadmaps, detailing existing solutions, needs, and ideas on how the field should further develop: the Nanoinformatics 2020 Roadmap and the EU US Roadmap Nanoinformatics 2030.

A 2013 workshop on nanoinformatics described current resources, community needs and the proposal of a collaborative framework for data sharing and information integration.

Introduction to electromagnetism

From Wikipedia, the free encyclopedia

Electromagnetism is the study of forces between charged particles, electromagnetic fields, electric (scalar) potentials, magnetic vector potentials, the behavior of conductors and insulators in fields, circuits, magnetism, and electromagnetic waves. An understanding of electromagnetism is important for practical applications like electrical engineering and chemistry. In addition, concepts taught in courses on electromagnetism provide a basis for more advanced material in physics, such as quantum field theory and general relativity. This article focuses on a conceptual understanding of the topics rather than the details of the mathematics involved.

Electric charge

Electric charge is a quantity used to determine how a particle will behave in an electric field. There are three possible "types" of charge: positive, negative, and neutral. However, the distinction between positive and negative is by convention only. Electric charge is quantized in units of the elementary charge, ${\displaystyle e}$, where a proton has a charge of ${\displaystyle +e}$ and an electron has a charge of ${\displaystyle -e}$. The SI unit of charge is the coulomb.

Millikan's oil drop experiment.

 

The elementary charge ${\displaystyle e}$ was first measured by Robert Millikan in his oil drop experiment in which the electric force on the particle is set to exactly counter the gravitational force that pulls it down, and the terminal velocity of this particle can be used to calculate its charge. A neutron has no electric charge. 

Charge conservation states that the overall electric charge in a closed system cannot change. Research suggests that the overall charge in the universe is neutral.

Electric field

Electric force

Coulomb's law states that the force on a charged particle due to the field from another particle is dependent on the magnitudes of the two charges as well as the distance between them. The further away the particle is, the weaker the force on it is. Positive charges exert attractive forces on negative charges (and vice versa) while positive charges exert repulsive forces on other positive charges (and similarly for the force between negative charges). The SI units of force are newtons (N).

The force between two like charges (above), and between two opposite charges (below).

Field lines

Michael Faraday and James Clerk Maxwell, first introduced the concept of a field in his 1831 paper on electromagnetic induction, (called "lines of magnetic and electric force" in this publication):

"...by line of magnetic force, or magnetic line of force, or magnetic curve, I mean that exercise of magnetic force which is exerted in the lines usually called magnetic curves, and which equally exist as passing from or to magnetic poles, or forming concentric circles round an electric current. By line of electric force, I mean the force exerted in the lines joining two bodies, acting on each other according to the principles of static electric induction."

Certain conventions are followed when drawing and interpreting electric field lines:

1. Electric field lines start at positive charges and end at negative charges;
2. The density of the field lines corresponds to the strength of the field in that area and thus to the strength of the charge;
3. The lines never cross, since otherwise the field would be pointing in two directions in one location; and
4. The vector arrow represents the motion that a positive charge would undergo if placed in the field, while a negative charge would follow the direction opposite the arrow.

The SI unit of the electric field is volt per meter (V/m), or equivalently, newton per coulomb (N/C). In mathematical expressions it is often represented as a vector-valued function ${\displaystyle {\vec {E}}}$. The electric field can be calculated in many ways, including Gauss' law, Coulomb's law, or Maxwell's equations. The electric field can also be interpreted as the electric force per unit charge.

Electric flux

The flux line representation of the field between two oppositely-charged particles.

 

Flux is dependent on the angle between the field lines and the surface through which they pass.

 

Flux can be thought of as the flow of the electric or magnetic field through a surface. Fields can be represented by flux lines. Flux is analogous to the flow of a fluid through a surface since the angle of the surface to the direction of flow determines how much fluid can flow through the surface. Gauss' law states that the flux through a closed surface is proportional to the amount of charge enclosed. The SI units of flux are newton meters-squared per coulomb (${\displaystyle Nm^{2}C^{-1}}$), or equivalently, volt-meters (V m).

Electric potential

Potential energy

The electric potential energy of a system of charges is the work it takes to assemble that configuration of charges. The energies add pairwise; that is, the work to bring a third charge into a system of two charges is the energy associated with the first and third charge plus that associated with the second and third charge. The potential energy of the system is unique to the configuration itself. The SI unit of energy is the joule (J).

Equivalently, it may be thought of as the energy stored in the electric field. For instance, if one were to hold two like charges a certain distance away from one another and then release them, the charges would move away with kinetic energy equal to the energy stored in the configuration. As an analogy, if one were to lift up a mass to a certain height in a gravitational field, the work it took to do so is equal to the energy stored in that configuration, and the kinetic energy of the mass upon contact with the ground would be equal to the energy of the configuration beforehand.

Potential

The electric potential is the potential energy per unit charge. The SI unit of electric potential is the volt (V).^[2] The potential difference between two points determines the behavior of a particle. Positive charges move from high potentials to low potentials, whereas negative charges move from low to high potential. This may be thought of in terms of fluid flow. Take two identical containers filled with a fluid to unequal volumes. One container is at a higher level (potential) while the other container is at a lower level (potential). If connected by a pipe (a wire), the fluid (charge) would flow from the left container to the right container until the fluid heights (potentials) are equal. Mathematically, the potential is the line integral of the electric field. The electric field can be represented as the change in the potential with respect to distance.

Conductors and insulators

Conductors

A conductor is a material that allows electrons to flow easily. The most effective conductors are usually metals because their electrons can move around freely. This is described in the electron sea model of bonding in which electrons delocalize from the nuclei, leaving positive ions behind while the electrons are shared by all atoms in the lattice. Examples of good conductors include copper, aluminum, and silver. Wires in electronics are often made of copper. 

The main tenets of conductors are as follows:

1. The electric field is zero inside a conductor. This is because charges are free to move and thus when they are disturbed by a field due to some external (or internal charge), they rearrange themselves such that the field that their configuration produces exactly cancels that caused by the source charge.
2. The electric potential is the same everywhere inside the conductor and is constant across the surface of the conductor. This follows from the first statement because the field is zero everywhere inside the conductor and therefore the potential is not changing with distance inside the conductor.
3. The electric field is perpendicular to the surface of a conductor. If this were not the case, the field would have a nonzero component on the surface of the conductor, which would cause the charges in the conductor to move around until that component of the field is zero.
4. The net electric flux through a surface is proportional to the charge enclosed by the surface. This is a restatement of Gauss' law.

Semiconductors are materials that, depending on their temperature, become better or worse conductors. Germanium and silicon are examples of superconductors. Superconductors are materials that exhibit little to no resistance to the flow of electrons when cooled below a certain temperature.

The fields inside each of these conductors is zero because the external field due to the central charge induces charges on the conductors to move around such that their fields cancel the external field inside the conductors.

Insulators

An insulator is a material with electrons that are more tightly bound and thus not able to move as freely as those of conductors. Insulators are often used to cover conducting wires so that charge will stay on the wire and will not go elsewhere. 

Charge can be distributed inside an insulator thus the electric field inside an insulator is not necessarily zero. Examples of insulators are plastics and polymers.

Magnetic field and force

Magnetic field

The magnetic field is that which arises from moving charges, currents, and magnetic objects. The field is represented mathematically as a vector-valued function ${\displaystyle {\vec {B}}}$. The SI unit of the magnetic field is the tesla (T).

The magnetic field can be derived mathematically using Ampère's law, the Biot–Savart law, or Maxwell's equations.

Magnetic field lines have a very similar representation to electric field lines. There is an analogous notion of magnetic flux. Magnetic field lines begin at north poles and end at south poles, and cannot cross. Magnetic fields arise due to the motion of charges, and also due to the alignment of the domains of magnetic materials where the magnetic moments of the atoms point in the same direction.

Magnetic field lines can be clearly visualized by sprinkling iron filings over a bar magnet.

 

The modern (post-Einstein) interpretation is that the magnetic field is equivalent to the electric field, but in a different reference frame. Since magnetic fields can be interpreted as electric fields in a different reference frame (and vice versa), special relativity connects the two fields. One postulate of special relativity is length contraction, and because of that, the charge density in the wire increases, so a current-carrying wire viewed in a moving reference frame experiences a length-contracted coulomb force as compared to the wire in a stationary frame. This force is called the magnetic force, and the associated field is the magnetic field. The direction of the magnetic force can be derived from the right-hand rule such that the force is perpendicular to both the direction of motion of the current (or charged particle) and the magnetic field.

Magnets

Permanent magnets make their own magnetic field. An example of a material from which a permanent magnet can be made is iron. It has a north and south pole, and cannot be split into a monopole — in other words, a north pole does not exist without a south pole.

Electrons moving around atoms can create a magnetic field if their effects sum up constructively. For magnetic materials like iron, the magnetic fields of the electrons moving around the nucleus add up, while for non-magnetic materials the effects average out to zero net magnetic field.

Inductance

Inductance is the ability of an object to resist a change in current. From Ampère's law one can conclude that the magnetic field within a coil of wire (also called a solenoid) is constant inside the coil and zero outside the coil. This property is useful in circuits to store energy within a magnetic field. 

Inductors resist change in currents, therefore it will produce a current opposing the change. This is also known as Lenz's law. Because of this property, inductors oppose alternating current.

Circuits

Circuits are connections of electrical components. Common components are as follows: 

Circuit components

Component	Main function	Schematic symbol
Resistor	Impedes the flow of current

Battery	Acts as a power source
Capacitor	Stores energy in electric fields, stores charge, passes low frequency alternating current
Inductor	Stores energy in magnetic fields, resists change in current

Current is defined as the change of charge per unit time, often represented as ${\displaystyle I}$and in units of amperes (A). Voltage is the difference in electric potential between two points in the circuit. In batteries, the potential difference is often called the emf (electromotive force) and is in units volt (V). 

Ohm's law states a relationship among the current, the voltage, and the resistance of a circuit: the current that flows is proportional to the voltage and inversely proportional to the resistance.

Direct current (DC) is constant current that flows in one direction. Alternating current (AC) is a current that switches direction according to a sinusoidal function, typically. Power grids use alternating current, and so residences and appliances are generally powered by AC.

Kirchhoff's junction rule

Kirchhoff's junction rule states that the current going into a junction (or node) must equal the current that leaves the node. This comes from charge conservation, as current is defined as the flow of charge over time. 

If a current splits as it exits a junction, the sum of the resultant split currents is equal to the incoming circuit.

Kirchhoff's loop rule

Kirchhoff's loop rule states that the sum of the voltage drops in a closed loop around a circuit equals zero. This comes from the conservation of energy, as voltage is defined as the energy per unit charge.

Parallel versus series

Components are said to be in parallel when the voltage drops across one branch is equal to that across another. Components are said to be in series when the current through one component is equal to that through another. Thus, the voltages across each path in a parallel circuit is the same, and the current through each component in a series circuit is the same.

Equivalent resistance in series is given by ${\displaystyle R_{equiv}=\sum _{k=1}^{N}R_{k}}$for ${\displaystyle N}$ resistors in series, while equivalent resistance in parallel is given by ${\displaystyle R_{equiv}={\frac {1}{\sum _{k=1}^{N}{\frac {1}{R_{k}}}}}}$ for ${\displaystyle N}$ resistors in parallel.

Equivalent capacitance in series is given by ${\displaystyle C_{equiv}={\frac {1}{\sum _{k=1}^{N}{\frac {1}{C_{k}}}}}}$, while equivalent capacitance in parallel is given by ${\displaystyle C_{equiv}=\sum _{k=1}^{N}C_{k}}$.

Electromagnetic waves

Electromagnetic spectrum

 

Electromagnetic waves are a result of Maxwell's equations which, in part, state that changing electric fields produce magnetic fields and vice versa. Due to this dependence, the fields form an electromagnetic wave, also called electromagnetic radiation (EMR). The electric and magnetic fields are transverse (or perpendicular) to each other, and transverse to the direction of propagation of the electromagnetic wave. From Maxwell's equations, one can show that electromagnetic waves propagate through a vacuum at speed

${\displaystyle c={\frac {1}{\sqrt {\epsilon _{0}\mu _{0}}}},}$

where ${\displaystyle \epsilon _{0}}$ is the permittivity of free space, and ${\displaystyle \mu _{0}}$ is the permeability of free space. Plugging in the values, one finds that ${\displaystyle c}$ is equal to the measured speed of light. Historically, this is what led Maxwell to suggest that visible light is an electromagnetic wave. Classified by wavelengths, electromagnetic waves include gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, and radio waves.