WSPC01494

• File Number: 8064.100
• Description: Ute Tribes
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 12/1/1986
• Author: Boyle Engineering
• Title: Southern Ute and Ute Mountain - Ute Indian Reservations - Agronomy Study - Sections 1-5
• Water Supply Pro - Doc Type: Report/Study

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1891
precipitation a year.

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3.4 RELATIVE HUMIDITY

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Humidity refers to water vapor in the air.

Relative humidity is

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atmospheric

vapor

pressure

expressed as a

percentage. The

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percentage represents the ratio of actual vapor pressure to the

saturation vapor pressure at a particular temperature. Atmospheric

moisture at saturation vapor pressure will condense on solid

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surfaces forming dew. The temperature at which this phenomenon

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occurs is known as the dew point. The dew point varies with the

atmospheric moisture content. Higher amounts of atmospheric

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moisture result in a higher dew point, while reduced atmospheric

moisture will yield a lower dew point.

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Relative

humidity

is

another

factor

which

influences

the

evapotranspiration rate.

The air takes up water transpired by the

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leaf or evaporated from the soil surface more rapidly as the relative

humidity decreases at a given temperature.

Temperature also

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affects the evapotranspiration rate. For example, the drying

capacity at 95 degrees is 9.2 times that at 32 degrees at the same
relative humidity. Evaporation and transpiration increase as a

result of high temperature and low relative humidity.

High

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seasonal evaporation from a free water surface is often related to

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high crop water requirements. Evaporation also affects rainfall

efficiency, particularly in areas that receive less than 30 inches

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3- 29

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