Glossary of Terms

Air particles -Extremely small objects that make up our atmosphere, such as gas molecules, dust and other microscopic debris.

Anti-cyclone - Fancy name for an area of high pressure. Low pressure systems are referred to as "cyclones", high pressure weather systems are somewhat opposite in nature and thus are referred to as "anti" cyclones.

Calibrate - To standardize (as a measuring instrument) or adjust precisely for a particular function.

Chlorofluorocarbon - (CFC) Aerosol propellants and in the manufacture of plastic foams, and that are suspected to be a major cause of stratospheric ozone depletion.

Cold Front - The leading edge of a mass of cooler air that is moving to replace a warm air mass.

Condensation - The process by which water vapor (gas) becomes liquid water. This process is opposite of evaporation or steam.

Convective -Atmospheric motions that are primarily up and down, such as rising currents due to surface heating.

Dew point - The temperature at which water vapor in the air starts to condense into liquid.

Evaporation -The process by which liquid changes into a gas. When water (liquid) is heated it evaporates and becomes steam (gas).

Equator - The equator is an imaginary line that runs around the earth ½ way between the North and South poles.

Equinox - there are 12 hours of day and 12 hours of dark at every location on Earth on the two equinoxes each year.

Fahrenheit - The temperature scale that is commonly used by Americans. 32 degrees is designated as the freezing point for fresh water and 212° is the boiling point of fresh water.

Gas - The name for matter that has no fixed volume or shape, air is a gas, helium gas is placed inside balloons.

High pressure - Aregion of sinking air where barometric pressure readings are higher relative to the surrounding areas .

Millibars - A unit for expressing atmospheric pressure. Sea level pressure is normally close to 1013 millibars.

Molecules - the smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms

Ozone Layer - A part of the Stratosphere which has a high concentration of Ozone gas.

Radiated - This is the term used to describe the method by which solar energy moves. This process is different from feeling heat above a flame or by touching a hot object. Radiated energy can travel through outer space for millions of miles.

Steam - The invisible vapor into which water is converted when heated to the boiling point.

Stratosphere - The layer of the atmosphere above the troposphere (between 12 and 50 miles), generally characterized by an increase in temperature with height.

Sea Level - The level of the surface of the sea especially at its mean position midway between mean high and low water.

Thermals - Parcels of air that become warmer and lighter than their surroundings and begin to rise.

Tropopause - The boundary between the troposphere and the stratosphere.

Troposphere - the layer of the atmosphere which extends from the earth's surface up to about 12 miles.

Warm Front - a transition zone where a warm air mass advances and replaces a cool air mass

Water Vapor - Water in a vapor or gaseous form.