HumidityThe amount of water vapor in the air.

Expressed two ways• Relative Humidity• Dew Point

Something to remember.

• Warm air can hold more water than cold air.

Relative humidity• Expressed as a percent.• Water vapor in the air/max amount the air can hold• Saturation- amount that the air can hold• Depends on temperature

Questions• How can you increase relative humidity with out changing the amount

of water vapor in the air?• Calculate the relative humidity for the following(cell phones ok)• 10g water vapor at 11C.• 10 g at 20C• 10g at 30C• 10g at 40 C• Write these in your notebook!

Dew point

• The temperature at which condensation takes place.• When air temp is cooled, saturation is reached.• Dew point is a better measure of actual water vapor because it does

not change with temperature. • How can the dew point go up?• How can the dew point go down?

Explain this picture. Use the terms dew point and saturation.