 As water evaporates from lakes, ocean and plants it becomes water vapor, or moisture in the air  Humidity is the amount of water vapor in the air Measured in g/m 3

 The air’s ability to hold water vapor changes as the temperature of the air changes. As the temperature of the air increases, the air’s ability to hold water vapor also increases.

 Relative humidity is… The amount of water vapor in the air compared with the maximum amount of water vapor that the air can hold at a certain temperature  Relative humidity is given as a percentage Humidity is NOT the same as relative humidity !

 When air holds all of the water vapor that it can hold at a given temperature, it is said to be saturated.  The two factors that affect the relative humidity are the amount of water vapor and temperature

 A psychrometer is an instrument that measures relative humidity  A psychrometer contains two thermometers, a dry-blub thermometer, which measures air temperature and a wet-bulb thermometer, which measures how fast the water evaporates off of the wet cloth  The difference between the wet-and dry- bulb readings indicates the relative humidity

Option 1: Cross Multiply Option 2: Ratio  Decimal  Percent  You MUST show all of you work  You can use calculators to check your work