1. Forms of Condensation

2. Condensation Condensation occurs when water vapor changes to a liquid.
For condensation to take place, the air must be saturated and there must be a surface on which the vapor can condense.
In the air above the ground, tiny hygroscopic (water-absorbent) particles known as condensation nuclei serve as the surfaces on which water vapor can condense.

4. Clouds
Clouds, visible aggregates of minute droplets of water or tiny crystals of ice, are one form of condensation.
Clouds are classified on the basis of two criteria: form and height.
The three basic cloud forms are:
cirrus (high, white, and thin),
cumulus (globular, individual cloud masses), and
stratus (sheets or layers).

5. Cloud Heights Cloud heights can be either:
high, with bases above 6000 meters (20,000 feet),
middle, from 2000 to 6000 meters, or
low, below 2000 meters (6500 feet).
Based on the two criteria, ten basic cloud types, including such types as cirrostratus, altocumulus, and stratocumulus, are recognized.

7. Cloud Types

9. Cirrus Clouds

10. Cumulostratus Clouds

12. Fog
Fog, generally considered an atmospheric hazard, is a cloud with its base at or very near the ground.
Fogs formed by cooling include:
radiation fog (from radiation cooling of the ground and adjacent air),
advection fog (when warm and moist air is blown over a cold surface), and
upslope fog (created when relatively humid air moves up a slope and cools adiabatically).

13. Fog (cont.) Those formed by evaporation are:
steam fog (when rising water vapor over warm water condenses in cool air) and
frontal fog (when warm air is lifted over colder air along a front).

15. Dew and White Frost
Dew is the condensation of water vapor on objects that have radiated sufficient heat to lower their temperature below the dew point of the surrounding air.
White frost forms when the dew point of the air is below freezing.

16. THE END