Thursday April 21, 2011. ( World Distribution of Temperature; Atmospheric Pressure ). The Launch Pad Thursday, 4/21/11. Define the term “air mass.”. A very large body of air, covering thousands of square miles, that contains similar temperature and humidity conditions throughout.
(World Distribution of Temperature; Atmospheric Pressure)
Define the term “air mass.”
A very large body of air, covering thousands of square miles, that contains similar temperature and humidity conditions throughout.
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Temperature maps help analyze temperature distribution over given areas.
Temperatures are adjusted to sea level to eliminate the variable of altitude.
January and July are used for analysis because they represent the temperature extremes.
On these maps, an isotherm is a line connecting places of equal temperature.
On a global scale, temperature patterns emerge.
The temperature decreases poleward from the tropics.
Isotherms exhibit a latitudinal shift with the seasons.
The warmest and coldest temperatures occur over land.
In the Southern Hemisphere, isotherms are straighter and more stable.
Isotherms show the annual temperature range of ocean currents.
Ranges are small near the equator, and increase with an increase in latitude
Ranges are greatest over continental locations.
World Mean Sea-Level Temperatures in January
World Mean Sea-Level Temperatures in July
Atmospheric pressure is the force exerted by the weight of the air above.
The weight of the air above at sea level is 14.7 pounds per square inch.
This pressure decreases with increasing altitude.
A common measurement unit of atmospheric pressure is the millibar(mb).
Standard sea level pressure is 1013.2 mb.
Another unit used in atmospheric pressure measurement is inches of mercury.
Standard sea level pressure is 29.92 inches of mercury.
The instrument used for measuring atmospheric pressure is the barometer.
The mercury barometer was invented by Torricelli in 1643.
It uses a glass tube filled with mercury.
Another type of barometer is the aneroid barometer, meaning “without liquid.”
This type of barometer uses an expanding chamber.
Another pressure instrument is the barograph, which continuously records the air pressure.
Air Masses, the Middle-Latitude Cyclone, and Weather Maps