2.  Heat Energy & Water:  Sublimation: process by which a solid changes directly into a vapor (gas).  When air is dry & temp below freezing, ice and snow may sublimate into water vapor.  Deposition: water vapor turning straight to ice. This is how frost is formed.

5.  Most water in atmosphere comes from evaporation: water absorbs heat from sun. Liquid into a gas.  The ocean is principal source of atmospheric moisture.

6.  Amount of water vapor in the atmosphere is known as humidity.  More evaporation means increased humidity.  Saturated – the air is holding as much vapor as it can at a given temp. As temp + air capacity + and vice versa.  Relative humidity – how close to saturation point. (g/m 3 ). Changes with temp.

7.  Specific humidity – actual amount of moisture in air. Number of grams of water vapor in 1 kg or air. Does not change with temp.  Dew point – Temp to which air must cool to reach saturation.

8.  Any temp below dew point means vapor condenses to liquid or solid by sublimation.  Air may cool to dew point when the air contacts a cold surface.  EX: grass, leaves and other objects at night  If dew point falls below the freezing temp of water, water vapor will change directly into solid ice crystals or frost.