| A | B |
|---|
| weather | the condition of Earth's atmosphere at a particular time and place |
| atmosphere | the layer of gases that surrounds a planet |
| nitrogen | the most abundant gas in Earth's atmosphere |
| water vapor | water in the form of a gas |
| oxygen | the gas that humans must breathe in order to live |
| ozone | a form of oxygen that has 3 atoms of oxygen |
| air pollution | harmful substances in the air |
| carbon dioxide | the gas plants need to produce food and live |
| smog | a combination of the words "smoke" and "fog" |
| fossil fuels | a natural fuel such as coal, oil, or gasoline, formed in the geological past from the remains of living organisms |
| photochemical smog | Air pollution produced by the action of sunlight on hydrocarbons, nitrogen oxides, and other pollutants |
| acid rain | rain that contains more acid than is normal due to air pollution |
| properties of air | mass, density, pressure |
| mass | a measure of the number of atoms in it |
| density | the mass of an object divided by its volume |
| air pressure | the force of air pushing down on an area or surface |
| barometer | an instrument used to measure a change in air pressure |
| mercury barometer | an instrument that has a glass tube partially filled with mercury |
| aneroid barometer | a baromter that measures changes in air pressure without using liquid |
| altitude | elevation-how high something is |
| sea level | the average height of the surface of the ocean (difference between high and low tide) |
| troposphere | at 0-12 km-lowest layer of Earth's atmosphere where we live and where weather happens |
| exosphere | above 550 km highest level of Earth's atmosphere and where phone calls and TV signals travel |
| stratosphere | at 12-50 km-contains the ozone layer and is right above the troposphere |
| mesosphere | at 50-80 km-meso means middle-where most meteors burn up |
| thermosphere | above 80 km-incudes the ionospere and the exosphere |
| aurora borealis | the Northern Lights that light up the night sky in the ionosphere |
