Air Temperature

(called “sensible” heat; air molecules get excited and vibrate faster as temp increases!)
I. What causes the air to heat or cool? (review net radiation – surpluses and deficits)
II. Air Temperature Lag: Because it takes time to heat the air, the warmest time of the day will follow the
maximum period of surplus of radiation by several hours. This is also true for the annual pattern or temperature.
The highest annual temperatures will follow the highest sun angles by a month or more.
III. Measuring Air Temperature – not at the ground for gosh sakes!!! (see text)
IV. Main Factors Affecting Temperature (called “Temperature Controls”)
A. Latitude: High latitudes receive lower sun angles; thus they have less total insolation than low latitudes.
Less insolation means lower temperatures.
B. Altitude: Recall that air temperature drops with increasing altitude. Called normal lapse rate. Basically,
mountains stick up into the cold air of the atmosphere.
C. Prevailing (Average) Wind Direction: Temperature in one place is commonly affected by air
coming from another place. For example, a strong north wind here in the winter usually brings extremely
cold temperatures.
D. Cloud Cover
1. Daily Temperature Range: Difference between the maximum and minimum.
2. Cloudy Skies: Sun (shortwave) blocked during day; clouds emit radiation toward Earth at night.
Results in lower daily temperature range. ie Days aren’t as hot, nights aren’t as cold.
3. Clear Skies: Earth receives high shortwave during day; longwave emitted toward space at night
(no counterradiation). Results in higher daily temperature range. i.e. Days are hot and nights are
cold.