Originally published in The Technology Teacher, May/June 2002, by the International Technology Education Association
A warm front is the transition area where a mass of warm air is moving in to replace a mass of cold air. But, the pressure gradient force isn’t the only force acting to move air. Other forces come in and really complicate things. The biggest stirrer of the atmospheric soup is Earth’s rotation. It causes the air north of the equator to tend to curve toward the right and the air south of the equator to curve to the left. This movement, of both air and oceans, is called the Coriolis effect.
Jet streams are fairly narrow bands of very high speed winds in the upper atmosphere. They generally blow from west to east. Strong tempera- ture differences cause great pressure differences (gradients) at high altitudes. These winds can reach 150 miles per hour or more. You can see why airline pilots flying across country from west to east like to take just the right route and fly at just the right altitude to get a kick in the tail (and save lots of fuel) from the jet stream—and why flying east to west, they try to avoid it!
Rain, snow, ice, and thunderstorms:
These terms need little explanation. These conditions are the end products of which we are all too aware! These forms of precipitation (water falling from the sky) result from the pressure gradients, cold fronts, and warm fronts, as well as ocean temperatures and currents, and a few dozen other factors.
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So with air moving in curves, interference (friction) from such obstacles as mountains, trees, and buildings, plus the heating and cooling of the atmosphere from day to night, you can begin to see why predicting the weather isn’t easy!
The United States has the wildest, most extreme weather of any country on Earth. Learn more about how weather works by reading this book . . .
Warm fronts usually move from southwest to northeast, bringing higher humidity. Warm fronts are usually drawn on a weather map using a solid red line, with half-circles on the side that points toward the cold air being replaced.
The Weather Book: An Easy-to-understand Guide to the USA’s Weather, by Jack Williams, pub- lished by USA Today.
. . . and by visiting these websites:
NOAA (National Oceanic and Atmospheric Ad- ministration) website, http://www.noaa.gov/
A cold front is the transition area where a mass of cold, dense (high pressure) air is moving in to replace warmer air. Cold fronts typically move from northwest to southeast. When a cold front passes through, the temperature can drop 15º F in an hour. A cold front is represented on a weather map by a solid line (usually blue), with triangles pointing toward the warm air it is replac- ing.
The University of Illinois Online Guides: Meteo- rology, http://ww2010.atmos.uiuc.edu/(Gh)/ guides/mtr/home.rxml
NOAA’s GOES Satellites home page, http://www.oso.noaa.gov/goes/ .
USA Today Weather, http://www.usatoday.com/ weather/wfront.htm .
GOES Project Science page, http:// rsd.gsfc.nasa.gov/goes/text/hotstuff.html .