Glossary

Air – A general word used for the gases and other particles that make up the atmosphere.

Air Mass – A large body of air, up to several hundred miles wide and several miles deep, that moves across the earth.

Air pressure – The force created by the atmosphere.

Anemometer – An instrument used to measure wind speed.

Atmosphere – The ocean of air, made up of gases, liquids, and solid particles, that surrounds the earth.

Barometer – An instrument used to measure air pressure.

Celsius – A scale that is used to measure temperature; 0 degrees is the freezing point of water and 100 degrees is the boiling point.

Cirrus – A thick high level cloud, made up of ice particles.

Cloud – A group of suspended water and/or ice particles in the air.

Condensation – When water vapor (a gas) changes to liquid water.

Cumulus – A cotton ball shaped cloud.

Dew – Small droplets of water found on surfaces, formed when temperatures on these surfaces reaches the dew point.

Dew Point – The temperature where air cannot hold additional moisture, and condensation will begin.

Equator – An imaginary line on earth halfway between the North Pole and South Pole.

Evaporation – When liquid water changes to a gas (water vapor).

Fahrenheit – A scale that is used to measure temperature; 32 degrees is the freezing point of water and 212 degrees is the boiling point.

Fog – A cloud at ground level.

Gas – A substance, often invisible, made up of small particles that can expand and contract, and move easily.

Greenhouse Effect – Warming of the atmosphere by slowing the release of heat to space, due to greenhouse gases such as carbon dioxide and methane.

Global Warming – Increased warming of the atmosphere due to increases in the amount of greenhouse gases such as carbon dioxide.

Hail – Pellets or balls of ice that form in layers.

Humidity – Water vapor in the air.

Hurricane – A large storm that forms in the ocean.

Lightning – Visible electrical discharge in the atmosphere.

Liquid – A substance that can easily flow, but cannot be squeezed together easily.

Nimbus – A prefix or suffix used to indicate precipitation is falling from a cloud.

Precipitation – Water, snow, or ice falling from a cloud.

Rain – Liquid water falling from a cloud.

Relative humidity – The actual amount of moisture in the air, compared to the maximum amount the air can hold for a specific temperature.

Revolution – The trip the Earth makes around the sun.

Rotation – The spin of the Earth.

Sleet – Rain that freezes just before it hits ground.

Solid – A firm substance that has a definite shape.

Snow – Precipitation made up of ice crystals.

Storm – A severe weather occurrence that may have rain, snow, wind, and lightning.

Stratus – A sheet or blanket type cloud.

Temperature – A measure of heat.

Thunder – Sound created by superheated air from lightning.

Tornado – A funnel shaped, spinning cloud with very high winds.

Weather – Day to day changes in temperature, wind, air pressure, and moisture in the atmosphere.

Wind – Air movement in the atmosphere.

Wind vane – An instrument used to measure the direction the wind is coming from.