Unformatted text preview: Elements of Meteorology Notes, Fall 2006 — 11:6702201 3. Base temperatures are determined locally. Most locations use 65 as the
base for both heating and cooling degree days, but some use 70 as a
base for cooling degree days. h. Controls of Temperature Latitude - Sun angle changes directly with latitude. Higher latitudes receive less
solar energy and are colder than lower latitudes. Altitude — Higher altitudes have lower temperatures. Location inland versus near a body of water — Water is a very good reservoir of
energy, evidenced by the fact that water temperatures change gradually over the
course of the year. As such, coastal locations have less range between high and
low temperatures than iniand iocations. i. On a weather map: E.
ii. 8. Moisture Isotherms are lines that connect points of equal temperature
isobars connect points of equal pressure a. Water exists in three states: i.
iv. Solid (Ice)
When water changes states, energy is released or absorbed. This energy is
referred to as “latent heat”.
1. Heat is absorbed during:
a. Meiting (solid to liquid)
b. Evaporation (liquid to gas)
0. Sublimation (solid to gas)
2. Heat is released during:
a. Condensation (vapor to liquid)
b. Freezing (liquid to solid)
c. Deposition (vapor to solid) b. Warm air can hold MUCH more water vapor than can cold air. .0 iv. vi. vii. viii. Moisture variables revisited
i. Dew point temperature — The temperature, to which if the air is cooled, the air will
be saturated, and dew or frost will begin to form.
Wet bulb temperature -— The lowest temperature attained by evaporating water
into the air, in other words, the air's “cooling power”.
Vapor Pressure — Portion of barometric pressure due to the presence of water
Saturated vapor pressure -— at some specific temperature, the pressure due to
water vapor when the air is saturated.
Mixing Ratio — Actual mass of water vapor per unit mass of air. Expressed in 9
water per kg air.
Saturated Mixing Ratio — Amount of water vapor in a kilogram of air when the air
is saturated at some specific temperature.
Relative Humidity - Ratio of the amount of water vapor in the air to amount of
vapor when the air is saturated. Expressed as a percentage.
1. (Vapor pressure I Saturated vapor pressure) x 100 percent
2. (Mixing ratio I saturated mixing ratio) x 100 percent
3. Relative humidity decreases when temperature increases if moisture
content remains constant, since saturated mixing ratios and vapor
pressures increase when temperature increases.
Temperature vs. Dew Point
1. Dew forms when air is cooled to its dew point. Since air is saturated at
this point, in order for temperature to fall, it must “squeeze" out some moisture. That moisture condenses on surfaces that are already cooler
than the air's dew point. ...
View Full Document
- Spring '08