| A | B |
|---|
| troposphere | layer of the atmosphere closest to Earth's surface, where most of the mass of the atmosphere is found and in which most weather takes place and air pollution collects. |
| stratosphere | layer of Earth's atmosphere that is located above the troposphere and is made up primarily of concentrated ozone. |
| mesosphere | layer of Earth's atmosphere above the stratosphere. |
| thermosphere | layer of Earth's atmosphere that is located above the mesopause; oxygen atoms absorb solar radiation causing the temperature to increase in this layer. |
| exosphere | outermost layer of Earth's atmosphere that is located above the thermosphere with no clear boundary at the top; transitional region between Earth's atmosphere and outer space. |
| radiation | the transfer of thermal energy electromagnetic waves; the transfer of thermal energy from the Sun to Earth by radiation. |
| conduction | the transfer of thermal energy between objects in contact by the collisions between the particles in the objects. |
| convection | the transfer of thermal energy by the movement of heated material from one place to another. |
| temperature inversion | increase in temperature with height in an atmospheric layer, which inverts the temperature-altitude relationship and can worsen air-polution problems. |
| humidity | amount of water vapor in the atmosphere at a given location on Earth's surface. |
| saturation | the point at which water molecules leaving the water's surface equals the rate of water molecules returning to the surface. |
| relative humidity | ratio of water vapor contained in a specific volume of air compared with how much water vapor that amount of air actually can hold; expressed as a percentage. |
| dew point | temperature to which air is cooled at a constant pressure to reach saturation, at which point condensation can occur. |
| latent heat | stored energy in water vapor that is not released to warm the atmosphere until condensation takes place. |
| condensation nucleus | small particle in the atmosphere around which cloud droplets can form. |
| orographic lifting | cloud formation that occurs when warm, moist air is force to rise up the side of a mountain. |
| cumulus | puffy, lumpy-looking clouds that usually occur below 2000 m. |
| stratus | a layered sheet-like cloud that covers much or all of the sky in a given area. |
| cirrus | high clouds made up of ice crystals that form at heights of 6000 m; often have a wispy, indistinct appearance. |
| precipitation | all solid and liquid forms of water - including rain, snow, sleet, and hail - that fall from clouds. |
| coalescence | process that occurs when cloud droplets collide and form larger droplets, which eventually become too heavy to remain aloft and can fall to Earth as precipitation. |
