ch 7 and part 8 GEOG 2050

# ch 7 and part 8 GEOG 2050 - Atmospheric Moisture Clouds...

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About 70% of earth is covered with water, most of it being in the ocean. In the atmosphere, water can be liquid, ice and water vapor The process of water coming from its liquid state and moving to the atmosphere in the gas form is called evaporation o Anytime there is any energy evaporation can occur. The more energy, the more gas molecules that will appear o Condensation is when gas comes out of the air and condenses into liquid form, or solid form The balance between these two processes is called saturation. Evaporation is equal to condensation. Saturated air does not occur that frequently. Any additional input of water in a saturated environment means that there will be some sort of cloud formation. o How do we know that the air is saturated? Cloud or fog formation o How do we know how close we are to saturation? Due point temperature: hypothetical temperature in the air in which you would get saturation. The higher the due point temperature is, the more moisture there is in the air. The temperature of the air is always greater than or equal to the due point temperature Vapor pressure: pressure exerted by water vapor molecules. o The warmer it is, the more evaporation will take place so there will be a higher vapor pressure. This is an exponential relationship. This shows that takes a little extra heat in the air to create a little extra water vapor. Warm air promotes more evaporation. o Saturation vapor pressure: max possible water vapor Ways to describe atmospheric moisture content: Dew point temperature Vapor pressure o The maximum number of water temperature has happened o Max possible: saturation vapor pressure is when the maximum evaporation has occurred Humidity: amount of moisture in the air. o Due point tells us relativity how much moisture is in the air; humidity is the actual measurement of moisture. o Absolute humidity : density of water vapor This is USELESS and very impractical o Specific humidity : mass of water vapor divided by the mass of all the air molecules. This is a theoretical concept but it is something that we can calculate, not necessarily measure The reason that specific humidity is used because it is useful for comparing humidity at different locations Final Exam Material

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o Relative humidity : amount of water vapor in the atmosphere compared to the maximum possible water vapor if the air is saturated Based on temperature as temperature goes up, the more evaporation is possible, greater possible water vapor maximum, and relative humidity goes down The warmest time of the day has the lowest relative humidity. At the coldest time (late at night) that is when there is the highest relative humidity. This explains why there is due on the ground and condensation on cars. If the relative humidity hits 100%, that means that the air is
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## This note was uploaded on 10/11/2011 for the course PSYC, PSYC 2076, 2060 taught by Professor Briganti,gustan,perlis,namikas,wheeler during the Spring '10 term at LSU.

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ch 7 and part 8 GEOG 2050 - Atmospheric Moisture Clouds...

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