Poisonous rain that can kill plants and animals. Scientists believe acid rain is caused by burning coal, oil, and natural gas. Pollutants, particularly sulfur dioxide and nitrogen oxide, mix with water in the air and then fall to the ground in the form of acid rain.
Ec[000000]f[16]LBargonB
Chemical symbol Ar. This colorless and odorless gas constitutes almost 1 percent of the atmosphere. It is mostly used in incandescent light bulbs, radio tubes, and welding. Ec[000000]f[16]LBatmosphere
B
The air around the earth. The atmosphere contains 78 percent nitrogen, 21 percent oxygen, and the remaining 1 percent is a combination of water vapor, carbon dioxide, argon, helium, and other gases.
Ec[000000]f[16]LBatom
B
The smallest unit of a an element. It is made up of protons, neutrons, and a positively charged nucleus surrounded by electrons. Atoms of an element combine to form molecules.
Ec[000000]f[16]LBcarbon dioxide
B
A natural component of the atmosphere, plants absorb carbon dioxide and water to produce the oxygen people breathe. However, increased amounts of carbon dioxide could be contributing to global warming, although there is speculation about the validity of this theory.
Ec[000000]f[16]LBcarbon monoxide
B
A colorless, odorless, poisonous gas that is produced when carbon is burned incompletely, meaning without a sufficient air supply. It is one of the main ingredients of smog.
Ec[000000]f[16]LBchlorofluorocarbons
B
Compounds containing chlorine, fluorine, carbon, and hydrogen; they are often used in refrigeration and cooling devices. Some scientists have speculated that the hole in the earth's ozone layer is caused by increased use of chlorofluorocarbons.
Ec[000000]f[16]LBcoal
B
The most abundant fossil fuel on earth. It is formed from living plants that died, decayed, and were buried by mud and other decomposing matter. It is located far underground. Therefore, deep mines and tunnels must be dug in order to extract coal deposits.
Ec[000000]f[16]LBcoke
B
Coke is coal that has had its gases removed through a heating process. When coke burns, it emits a great deal of heat but very little smoke. It is usually used as an industrial fuel.
B Ec[000000]f[16]BLcondense
B
To change from a vaporous or gaseous state to a liquid state; for example, steam condenses to form water drops.
Ec[000000]f[16]LBconserve
B
To preserve or maintain environmental conditions and resources, including wildlife or vegetation.
Ec[000000]f[16]LBconsumers
B
In ecology, consumers are animals that eat plants or other animals. They are the opposite of producers, which are plants that make their own food energy using the sun as an energy source.
B Ec[000000]f[16]BLdecomposer
B
An organism that breaks down dead organic matter into simpler molecules. Decomposers, such as fungi or bacteria, are the final link in the food chain.
Ec[000000]f[16]LBdiesel fuel
B
A type of fuel used in internal combustion engines. These engines are ignited after heat compresses the air.
Ec[000000]f[16]LBecology
B
The scientific study of organisms and their relationships with each other and with the environment, including all living and nonliving components.
Ec[000000]f[16]LBecosystem
B
The system of living and nonliving parts in an environment and the relationships among all of these parts.
Ec[000000]f[16]LBendangered species
B
A plant or animal that is threatened with extinction, either by natural forces or, more commonly, by the acts of human beings.
Ec[000000]f[16]LBenergy
B
Energy can be chemical, electrical, mechanical, nuclear, or thermal, and is measured in joules. In the context of physics, energy is the ability to do work. However, it also refers to a power that is inherent, or existing naturally, within someone or something and the capacity Ec[000000]f[16]LFfor great action or strength. Energy can be produced from petroleum, coal, gas, wind, nuclear fuel, and sunlight, in the form of electricity and heat. Ec[000000]f[16]LBerosion
B
The deterioration of the earth's soil and rock surfaces because of the constant exposure to wind, water, and other natural forces. Materials from those surfaces are blown or washed away to other areas.
Ec[000000]f[16]LBevaporate
B
To change from a liquid state to a vaporous state; for example, water evaporates into steam.
Ec[000000]f[16]LBEverglades
BAn almost tropical marshland in southern Florida that is about forty miles wide. The Everglades National Park, located in the southern part of the Everglades, is a wildlife refuge and biosphere reserve. Ec[000000]f[16]LBextinct
B
A species that no longer has any living members, or that no longer exists. Both plants and animals are susceptible to extinction.
Ec[000000]f[16]LBfirst-level consumerB
A consumer, such as a deer, bird, rabbit, or cow, that eats plants and is in turn eaten by a second level consumer.
B Ec[000000]f[16]BLfission
B
The splitting of an atom into two parts, resulting in the release of a tremendous amount of energy. In nuclear energy systems, uranium atoms are split.
Ec[000000]f[16]LBfood chain
B
The transfer of energy from producers to consumers. Producers are eaten by consumers, who are in turn eaten by other consumers, and so on. For example, a plant is eaten by a rabbit, who is then eaten by a coyote. The food chain assumes that the consumers in each level Ec[000000]f[16]LFonly eat the organisms below them on the chain.
Ec[000000]f[16]LBfood web
B
An assembly of food chains that overlap or are related to each other.
Ec[000000]f[16]LBfossil fuels
B
Energy sources that are formed from the decayed remnants of organisms that lived millions of years ago and can be burned to produce fuel. The three fossil fuels are coal, natural gas, and petroleum, or crude oil.
Ec[000000]f[16]LBfungi
B
Plural of fungus; organisms that are decomposers, or that feed on dead material and lack chlorophyll, roots, and stems. Included in the division of fungi are mildews, molds, and mushrooms.
Ec[000000]f[16]LBgeothermal
B
In terms of energy, geothermal refers to heat that comes from the earth's interior. Geysers are natural examples of this type of energy. Potentially the most productive alternative energy source, geothermal energy is produced deep below the earth's surface, from heat that scientists believe Ec[000000]f[16]LFis caused by the decay of radioactive materials. The heat produces magma, or molten rock, which heats underground water that then produce steam.
Ec[000000]f[16]LBgeyser
B
A spring that gushes streams of hot water and steam into the air at frequent intervals.
Ec[000000]f[16]LBglobal warming
B
The controversial theory stating that increased carbon dioxide in the air is causing the atmosphere to heat up. Some scientists speculate that global warming is occurring right now.
Ec[000000]f[16]LBgreenhouse effect
B
The greenhouse effect is the result of many pollutants in the air. Scientists postulate that increased carbon dioxide in the air is causing the atmosphere to heat up, much like the inside of a greenhouse. This trend could contribute to global warming, which could alter the balance of earth's living systems.
Ec[000000]f[16]LBhabitat
B
The area where an organism naturally lives or grows.
Ec[000000]f[16]LBhumus
B
Special microbes, such as bacteria and fungi, cause organisms in the soil to decay, and this part of the soil is called humus. The decaying process helps return nutrients to the soil.
Ec[000000]f[16]LBhydroelectric energy
B
An alternative energy resource to fossil fuels. One percent of the world's energy comes from hydroelectric power, or electric energy produced from moving water. The moving water, usually from a dam or a waterfall, turns a turbine, which then turns an electric generator.
