Temp 54 Dew Point 41 Relative Humidity 63%

Transcription

1 Temp 54 Dew Point 41 Relative Humidity 63%

2 Water in the Atmosphere

3

4 Evaporation Water molecules change from the liquid to gas phase Molecules in liquids move slowly Heat energy makes them move faster When the molecules move fast enough, they become a gas called water vapor Water molecules as a liquid Water molecules as a vapor A typical glass of water

5 Water Makes up 75% of the surface of the earth Only 2% of total water is fresh water Exists on Earth in 3 forms Freezing Condensing Solid - Ice Liquid - Water Gas - Vapor Melting Evaporating

6 Transpiration Water transferred from plants to the atmosphere helps to cool the atmosphere. Plants draw water out of the ground Water vapor is released to the air when gases are exchanged

7 Condensation Water molecules changing from a gas to a liquid phase Water vapor molecules have a lot of heat energy and move fast When they lose heat energy they slow down When enough slow moving water molecules collect in one place they condense into droplets (dew) When the air temperature is below 0 o C (32 o F) water can condense into ice crystals (frost) Dew Point - the temperature at which water vapor condenses

8 Precipitation Any form of water that forms from clouds and returns to the earth Common Types: Rain Freezing Rain Snow Sleet Hail

9 4. Deep ground water and runoff return water to the rivers, lakes, and oceans The Water Cycle 1. Heat energy from the sun warms surface water on the earth, causing it to evaporate 3. Precipitation (rain, snow, hail) returns water to the soil 2. Evaporation and transpiration returns water to the atmosphere

10 Humidity A measure of the amount of water vapor in the air Warm air holds more moisture than cool air Air feels cooler when the humidity is lower, the air is more capable of evaporating water from sweat Measured with an instrument called a Psychrometer Wet Bulb Dry Bulb

11 Relative Humidity The percentage of water vapor in the air compared to the maximum amount the air could hold If the air can hold 8 grams of water, and it has 8 grams, the relative humidity would be 100% If the air can hold 8 grams of water, and it has 4 grams, the relative humidity would be 50% Saturation - When the air is holding all that can be held at a given temperature. RH = 100%

12 Dew Point The temperature in the atmosphere at which water vapor turns into water. The closer the dew point is to the air temp the higher the relative humidity. Dew point 46 Air Temp 64 RH = 52% Dew Point 64 Air Temp 64 RH = 100% Dew Points in the 60 s and 70 s is tropical air, very humid

13

14

15 Clouds Clouds form when water vapor condenses into water or ice crystals in the air Clouds form when the temperature falls below the dew point Small particles of dust must be present for the water to condense

16 Clouds Three Basic Types: Cumulus: Vertically Developed Stratus: Low Level Cirrus : High Level

17 Cumulus Clouds Thick and puffy, cotton candy clouds associated with fair weather

18 Name That Cloud Swelling Cumulus

19 Cumulonimbus clouds are vertically developed clouds that can yield lightning, hail, and heavy rainfall.

20 Stratus Clouds Low level layer of clouds that often covers the entire sky. Nimbostratus clouds are heavier stratus clouds that give long periods of steady rain or snow.

21 Cirrus - Wispy, feather clouds Only form at high levels Made mostly of ice crystals

22 Fog is a low-lying cloud at or near the surface of the earth

23

24 Precipitation Rain - Droplets of water greater than 0.5 mm in diameter Drizzle - Droplets of water less than 0.5 mm in diameter Sleet - When rain falls through freezing air and turns to ice Freezing rain - When rain strikes a cold surface and turns to ice

25

26

27

28

29 Precipitation Snow - Ice crystals formed inside a cloud, form in the presence of little wind Hail - Pellets of ice greater than 5 mm in diameter. Form exclusively inside cumulonimbus clouds and are associated with storms

30

31 Hail forms in cumulonimbus clouds.