Earth Science Chapter 18 Vocabulary
Read the definitions below, rewrite the definition in YOUR OWN WORDS, and then draw a
picture that shows you understand the meaning of each word.
Cirrus: High altitude clouds that are thin, feathery tufts of ice crystals.
Condensation: The change from water vapor to liquid.
Condensation level: The altitude at which water vapor begins to condense.
Condensation nuclei: Microscopic particles on which water vapor condense to form cloud
droplets.
Cumulus: Thick fluffy clouds with flat bases formed by vertically rising air currents.
Dew point: The temperature at which saturation occurs and condensation begins; a measure of
the amount of water vapor in the air.
Freezing rain: Super-cooled raindrops that freeze instantly when they hit a solid surface.
Hail: Small, nearly spherical pieces of ice made up of concentric layers formed by the successive
freezing of layers of water.
Precipitation: Any form of water that falls from a cloud to Earth’s surface, such as rain, snow,
sleet, and hail.
Relative humidity: A comparison of the actual amount of water vapor in the air with the
maximum amount of water vapor that can be present in air at a given temperature and pressure.
Saturated: The condition in which the air is holding as much water vapor as possible at a given
temperature and pressure.
Sleet: Clear ice particles formed when raindrops freeze before they reach the ground.
Specific humidity: The amount of water vapor in the air at a given time and place; expressed as
the number of grams of water vapor per kilogram of air.
Stratus: Clouds that form in low, horizontal layers.
Water vapor: An invisible gas formed when water reaches 100°C or above and evaporates.