Clouds and Fog

Section 24.2

Cloud Formation

• Clouds result from the condensation of water vapor in the atmosphere

• Suspended particles of ice, slat, dust, etc, provide the surfaces necessary for the cloud-forming condensation. These particles are called condensation nuclei.

Adiabatic Temperature Changes

• Are changes in temperature that result from the expansion or compression of air

• For dry air, temperature of dry air decreases about 1°C for every 100 m

• For moist air it varies from 0.5°C to 0.7°C per 100m

Condensation Level

• When the air reaches a level where its temperature is lower than its dew point, the moisture in the air condenses to form a cloud

Forceful Lifting

• Air can be forced up quickly when it encounters a mountain range

• During storms, warm air is pushed above denser cooler air

Classification of Clouds

• Clouds are classified by their form and altitude

• Low clouds – up to 2000 m

middle clouds -2000-6000 m

high clouds – above 6000 m

Stratus clouds

• Sheetlike, layered clouds. These are the most extensive clouds in the sky.

• Little rain usually falls from these kinds of clouds

• Varieties: nimbostratus, altostruatus

Cumulus

Cumulus CLouds

Cirrus Clouds