| A | B |
|---|
| air | Mixture of gases surrounding the earth and forming its atmosphere |
| air mass | Large body of air that has uniform temperature and humidity. These have distinct boundaries and can extend 100s or 1000s of miles |
| air pressure | Force exerted on a surface by the weight of air above it (aka atmospheric pressure) |
| anemometer | Instrument used to measure wind speed |
| aphelion | The point in an orbit where a planet is farthest from the Sun |
| barometer | Instrument used to measure air pressure |
| climate | Pattern of weather conditions established over many years or centuries |
| climatology | The study of weather conditions over a long period of tiime |
| cloud | Visible accumulation of water on condensation nuclei, either as liquid or ice, usually high in the air. |
| condensation nucleus | A small particle on which water vapor condenses |
| conduction | The transfer of energy from one place to another by direct contact |
| ccnvecton | Movement of a fluid, such as air, that transfers heat from one place to another. |
| Ccnvection cell | cycle caused by convection when cool, denser material sinks and replaces warmer, less dense material |
| Coriolis effect | The apparent deflection of winds due to Earth's rotation |
| Dew | Water that condense on surfaces when the temperature drops below the dew point. |
| dew point | The temperature at which a volume of air is saturated with water vapor; condensation occurs when the temperature drops below the dew point |
| dust devil | small rotating wind not associated with a thunderstorm, visible when it collects dust and debris |
| equinox | When day and night hours are equal length everywhere. Happens twice a year on about March 21 and September 23 |
| evaporation | Process in which liquid water becomes water vapor |
| exosphere | Outermost layer of the atmosphere, where the atmosphere makes the transition to space |
| front | the leading edge of a moving air mass |
| frost | Frozen dew. Forms when the dew point is below 0 degrees C |
| global wind | Wind that affects large sections of Earth, such as trade winds |
| greenhouse effect | The heating of the atmosphere by trapped solar radiation |
| hail | Precipitation in the form of balls of ice |
| heat | A form of kinetic energy that raises the temperature of a substance |
| humidity | Water vapor in the air |
| hurricane | A cyclone or moving wind system that rotates around an eye. |
| hygrometer | an instrument used to measure relative humidity |
| ionosphere | Layer of the atmosphere within the thermosphere; noted for its large number of electrically charged ions. |
| kinetic energy | energy of motion |
| land breeze | local wind that blows FROM LAND toward the sea |
| lightning | A visible electric discharge produced by thunderstorms |
| mesosphere | layer of the atmosphere above the stratosphere, in which temperature decreases and meteors burn up when approaching Earth |
| meteorologist | scientist who studies the causes and effects of Earth's weather |
| methane | colorless, odorless greenhouse gas composed of carbon and hydrogen |
| millibar (mb) | A unit of measurement for air pressure. |
| nitrogen | the most abundant (plentiful) gas in Earth's atmopshere. It does not react with other substances (it's stable) |
| oxygen | Second most abundant gas in Earth's atmosphere; colorless, odorless and tasteless gas |
| ozone | contains three atoms of oxygen; shields Earth from harmful UV rays; close to ground it is a main component of smog |
| perihelion | The point in an orbit where a planet is closest to the Sun. |
| radiation | Energy transmitted through space in the form of rays, waves, or particles. |
| relative humidity | The amount of water vapor in the air compared to the amount of water vapor needed to saturate the air at a given temperature |
| saturated | holding as much water vapor as possible |
| solstice | when the sun is at its greatest distance from the equator; twice yearly around June 21 and December 21 |
| temperature | A measure of the average kinetic energy of the molecules in a material |
| thermosphere | thin layer of the atmosphere above the mesosphere where temperature may reach more then 1500 degrees C |
| troposhere | layer of the atmosphere next to Earth's surface in which we live and in which weather takes places |
| water vapor | invisible, gaseous form of water |
