| A | B |
|---|
| acid rain | rain that is more acidic than normal; caused by the releaseof molecules of sulfer dioxide and nitrogen oxide into the air |
| air pressure | a force that is the result of the weight of a column of air pushing down on an area |
| altitude | elevation above sea level |
| aneroid barometer | an instrument that measures changes in air pressure without using liquid. Changes in the shape of an airtight metal box cause a needle to on the barometer dial to move |
| atmosphere | the mixture og gases that surround Earth; the outer most of the 4 spheres into which scientists divide Earth |
| aurora borealis | a colorful,glowing display in the sky caused when particles from the sun strike oxygen and nitrogen atoms in the ionosphere;also called the Northern Lights |
| barometer | an instrument used to measure changes in air pressure |
| density | the measurement of how much mass of a substance is contained in a given volume |
| exosphere | the outer layer of the thermosphere, extending outward into space |
| ionosphere | the lower part of the thermosphere,where electrically charged particles called ions are found |
| mercury barometer | an instrument that measures changes in air pressure, consisting of a glass tube partially filled with mercury, with its open end resting in a dish mercury. Air pressure pushing on the mercury in the dish forces the mercury in the tube higher |
| mesophere | the middle layer of the Earth's atmosphere; the layer in which most meteroids burn up |
| ozone | a form of oxygen that has three oxygen atoms in each molecule instead of the usual two;can be toxic |
| photochemical smog | a brownish haze that is a mixture of ozone and other chemicals, formed when nitrogen oxides,hydrocarbons, and other pollutants react with one another in the presents of sunlight |
| pollutant | harmful substances in the air,water or soil |
| pressure | the force exerted on a surface divided by the total area over which the force is exerted; also the force of a gas's outward push divided by the area of the walls of the container |
| stratosphere | the second- lowest layer of the Earth's stratosphere; the ozone layer is located in the upper stratosphere |
| temperature inversion | condition in which a layer of warm air traps polluted air close to Earth's surface |
| thermosphere | the outermost layer of Earth's atmosphere |
| troposphere | the lowest layer of the Earth's atmosphere, where weather occurs |
| water vapor | the invisible, gaseous form of water |
| weather | the condition of the Earth's atmosphere at a particular time and place |
