Urban Heat Island Effect
The Urban Heat Island Effect is a situation in which an urban area becomes more heated than the surrounding rural areas. There are heat islands on the surface and in the atmosphere. Urban areas become warmer and the surface becomes dry because buildings, roads, and high populations make an "island" of higher temperatures. Urban Heat Islands affect a community and the people's way of life. It may seem positive because it increases the length of plant life, but it has many other concerning effects. First, it increases energy consumption. Heat Islands are responsible for a peak of electricity usage in the summers. Next, a high energy demand results in a large emission of greenhouse gases and air pollutants. Also, Heat Islands create general discomfort, not only illness because of heat, but also because air pollutants can cause respiratory difficulties. Finally, the Urban Heat Island Effect can impair water quality. Temperature changes in water can be harmful to aquatic ecosystems. In Gilbert, Arizona, and Tuscan, Arizona, cool roofs, cool pavements, and trees and vegetation are used to reduce the heat resulted from UHI. Another way to mitigate the impact of UHI is by installing a "green roof." Combining multiple of these strategies is the most effective way to reduce the effects of Urban Heat Islands.
Aerosols
Aerosols are tiny particles that are suspended in the atmosphere. When they get larger, they scatter into and absorb sunlight. When the sunlight is scattered, it reduces haze and causes sunrises and sunsets to be reddened. Aerosols are important because they affect the Earth's climate and radiation budget. In a direct way, they carry sunlight back into space. Indirectly, aerosols in the lower atmosphere can change the size of cloud particles, which changes how clouds absorb and reflect sunlight, which affects the Earth's usage of energy. Aerosols are also sites for chemical reactions to take place. The reactions that take place on these large cloud particles form highly reactive chlorine and result in the destruction of the ozone.Volcanic aerosols are formed by sulfur dioxide gas, which converts into sulfuric acid droplets. Desert dust from over the Atlantic Ocean and deserts in Asia also create aerosols. Aerosols also come from human activities. Burning coal and oil forms sulfate aerosols. In fact, human made sulfate aerosols outweigh natural sulfate aerosols. These aerosols enter clouds, which reflect sunlight. Additional reflection caused by pollution aerosols actually cools areas.
Greenhouse Effect
The greenhouse effect is a process where radiation is absorbed by greenhouse gases in the atmosphere and is re-radiated in all directions. This re-radiation causes global temperatures to get warmer because the gases are being put into lower parts of the atmosphere. Carbon Dioxide, Methane, and Nitrous Oxide are the top three greenhouse gases. Greenhouse gases are gases that trap heat in the atmosphere. The increase of greenhouse gases in the atmosphere is caused by human activity. Burning fossil fuel for electricity, heat, and transportation is a major source of greenhouse gases. Also agriculture and land use create greenhouse gases. Infrared radiation is related to global warming and the greenhouse effect. It is a light with a longer wavelength than the red color in the visible part of the spectrum, but shorter than microwave radiation. It may be perceived as heat. The Earth's surface and atmosphere give off infrared radiation.
