Class Notes (836,862)
United States (324,794)
Geography (207)
GEOG 1112 (23)
Lecture 10

GEOG 1112 Lecture 10: Humidity

3 Pages
Unlock Document

GEOG 1112
James Shepherd

LECTURE 10 | HUMIDITY The Hydrologic Cycle • Earth has been called the “water planet” as over 3⁄4 of the Earth’s surface is covered by water. • Water is unique in that it can simultaneously exist in all three states (solid, liquid, gas) at the same temperature and shift between states easily. • The hydrologic cycle refers to the cycle of water through the earth and atmosphere. Distribution of Water Vapor • The hydrologic cycle refers to the cycle of water through the earth and atmosphere. Atmospheric Humidity • Humidity: A generic term for the amount of water vapor present in the air. Ways to Express Humidity • Absolute Humidity: o mass WV in air (g) / volume of air (m3) • Specific Humidity: o mass of WV in air (g) / total mass of air (kg) • Mixing Ratio: o mass of WV in air (g) / mass of dry air (kg) Vapor Pressure • The amount of atmospheric pressure exerted by water vapor molecules. • We can measure vapor pressure in the same way as with total pressure, in millibars... Saturation • Saturation: the maximum amount of water that can exist in the atmosphere as a vapor at a given temperature. • This occurs when evaporation = condensation • We can look at saturation values for each of the measures of atmospheric humidity: o Saturation Vapor Pressure o Saturation Specific Humidity o Saturation Mixing Ratio Processes That Cause Saturation • Air may become saturated through 3 ways: o the addition of water vapor o mixing cold air with warm air o moist air—by cooling the air to dew point • If enough vapor is added to the air to saturate it, a precipitation fog forms beneath the cloud (#1 listed above) Relative Humidity • This is probably the most familiar measure of water vapor content. • It is the amount of water vapor present relative to its saturation point (e.g. the maximum possible at the current temperature). • RH = actual amount of WV/ capacity that can be held for a given temperature • We can plug in specific humidity for “actual” and saturation specific humidity for “saturation” or “capacity” value. • RH = (specific humidity / saturation specific humidity)*100% • Relative Humidity does not uniquely determine the
More Less

Related notes for GEOG 1112

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.