Weather Factor #4: Water

Water Cycle

EvaporationLiquid water gains heat and turns into water vapor.

CondensationWater vapor loses heat and turns into liquid water.

PrecipitationWater falling from the sky.TranspirationThe process of emitting water vapor through the leaves of plants .Weather Factor #4:WaterWater in the atmospherevaporclouds6HumidityMeasure of the amount of water vapor in the air.Amount depends on the air temperature.Warm air can hold more water vapor.7Relative HumidityPercent of water vapor that is actually in the air compared to the maximum amount it can hold at a particular temperature.8Tool to measure relative humiditySling Psychrometer

9Relative HumidityExampleat 10 degrees Celsius 1 cubic meter of air can hold 8 grams of water vapor; if there were 8g of vapor in the air then the relative humidity would be 100%.What would the relative humidity be if the same cubic meter of air had 4 g of water vapor? 50 %10

at 10 degrees Celsius 1 cubic meter of air can hold 8 grams of water vapor; if there were 8g of vapor in the air then the relative humidity would be 100%.Relative humidity is 25%, how many grams of water?2 g

11What happens if the temperature of the air increases?Warm air can hold more water

12Why might condensation occur if air is cooled enough?The amount of water in the air would become greater than the air could hold.13Dew PointThe temperature at which condensation begins.

Must have surface to condense on.Dew point below 0 degrees C Frost14Condensation forms clouds.Tiny particles in the atmosphere provide surface for water vapor to condensate on.DustSaltSmoke

15CloudsStratus- flat layered clouds, spread out usually cover the sky. Low level clouds.

16Cumulus Fluffy rounded piles of cotton. Low level clouds.

17Cirrus Wispy, feathery clouds. High level clouds.

18Add-ons Alto- highAltostratus Altocumulus Nimbo/Nimbus- rainNimbostratusCumulonimbus 19Precipitation Rain. Sleet- as rain falls through air that is below 0 C it freezes.Freezing rain- rain freezes as it hits cold surface.Snow- vapor converted directly to ice crystals.Hail- ice pellets, updrafts push it back into the cumulonimbus cloud where it grows.

20Cloud SeedingSilver oxideDry ice21