Water in the Atmosphere

States of Matter - Water melting evaporation Solid Liquid Gas freezing condensation

Energy Transfer – Phase Changes

energy gained = environment cools down energy released= environment heats up

Latent Heat Energy is required to break the hydrogen bonds that hold water molecules together Energy is taken from the environment and is stored in the water molecule This energy is called latent heat Energy is released during condensation/freezing

Humidity Humidity – measure of the amount of water vapor in the air Warm air holds more water vapor than cold air Relative Humidity – the percentage of water in the air, relative to how much it can hold Saturated - when air can’t hold any more water vapor Condensation occurs Dew point – temperature at which saturation occurs Measured with a sling psychrometer

Sling Psychrometer

Question: If the dry-bulb temperature is 20o C and the wet-bulb temperature is 12o C, what is the dewpoint?

Question: If the dry-bulb temperature is 12o C and the wet-bulb temperature is 10o C, what is the dewpoint?

Question: Use the sling psychrometer and determine what temperature the air in the room would have to be reduced to for the moisture in the air to condense.

Question: If the dry-bulb temperature is 24o C and the dewpoint is 2o C, what is the wet-bulb temperature? Dry-Bulb - ∆ W-B & D-B Web-Bulb 24o C - 11o C 13o C