Geography 120 Ch.5

measure of water vapor content or density of water vapor. Not widley used because it is dependent on temperature even though the amount of vater vapor never changes. it does this because if an air parcel expands the absolute humidity will fall.

expresses the mass of water vapor existing in a given mass of air.

most commonly used measure of water vapor content. relates amount of water vapor in the air to the maximum possible aat the current temperature.

moisture index free of temperature relationship. it shows the temperature at which saturation occurs.

• 1. adding water vapor to the air
• 2. mixing of cold air and warm air
• 3. lowering temperature to dew point

water having a temperature below the melting point of ice but nonetheless existing in a liquid state. this occurs at temperatures between 0 and -4 C.

when energy is added to or removed from a system resulting in changing temperature

when temperature changes but no heat is added to or removed from a substance.

a parcel of unsaturated air cools 1 degree Celsius for every 100 meters of asent despite the fact that no heat is removed.

when a parcel of air rises high enough and cools sufficiently, expansion lowers its temperature to te dew or frost point and condensation or deposition commences.

for every 100 meters a parcel of air rises it loses .5 degrees celsius.

applies to the vertical change in temperature through still air. the rate at which an ambient parcel of air decreases with height. the ELR for the troposphere is highly variable.

also known as ground fog, develop when nighttime loss of longwave radiation causes cooling to the dew point. it is likely to form ON CLOUDLESS NIGHTS WITH LIGHT WINDS. in the early moring the fog will burn off.

forms when relatively warm, moist air moves horizontally over a cooler surface. (term advection refers to horizontal movement). As the air passes over the cooler surface it transfers heat downward; this causes it to cool diabatically. If sufficient cooling occurs, a fog forms. San Franciso Bay area.

formed by adiabatic cooliing., when air flows along a gently sloping surface, it expands and coolsas it moves upward. Seen a lot west of the mississippi river.