Unit 8

Troposphere

Layer of the atmosphere closest to Earth’s surface where most weather takes place and air pollution collects.

Stratosphere

Layer of Earth’s atmosphere located above the tropopause, primarily made up of concentrated ozone.

Mesosphere

Layer of Earth’s atmosphere above the stratopause.

Thermosphere

Layer of Earth’s atmosphere located above the mesopause where oxygen atoms absorb solar radiation, causing temperature to increase.

Exosphere

Outermost layer of Earth’s atmosphere above the thermosphere with no clear boundary, transitional region to outer space.

Radiation

The transfer of thermal energy by electromagnetic waves, including from the Sun to the Earth.

Conduction

The transfer of thermal energy between objects in contact via particle collisions.

Convection

The transfer of thermal energy by the movement of heated material.

Greenhouse effect

Natural process where atmospheric gases absorb heat from Earth’s surface, aiding in temperature maintenance.

Temperature inversion

Increase in temperature with height in the atmosphere, reversing the temperature-altitude relationship.

Humidity

The amount of water vapor present in the atmosphere at a specific location.

Saturation

The point at which water molecules leaving the surface equals those returning to it.

Relative humidity

Ratio of water vapor in a specific volume of air to the amount the air can hold, expressed as a percentage.

Dew point

The temperature at which air cools to reach saturation and condensation occurs.

Latent heat

Stored energy in water vapor not released until condensation occurs.

Condensation nucleus

Small particle in the atmosphere around which cloud droplets form.

Orographic lifting

Cloud formation occurring when warm, moist air rises over a mountain.

Cumulus

Puffy, lumpy-looking clouds typically occurring below 2000 m.

Stratus

Layered sheet-like clouds covering much or all of the sky.

Cirrus

High clouds made of ice crystals forming at heights of 6000 m.

Precipitation

All solid and liquid forms of water falling from clouds, including snow and sleet.

Coalescence

Process where cloud droplets merge to form larger droplets, leading to precipitation.