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Unit 6: Local and General Winds

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Measuring Winds Aloft and Wind Profiles

Now let us turn our attention to the fact that air in the atmosphere is constantly moving, and its speed can vary by heights into the atmosphere. Winds aloft are measured at weather observation stations throughout the world by using radiosonde balloons. (See graphics above) An instrument package is suspended from the lighter-than-air balloon. These instruments are released at regular intervals by observers. The balloon is tracked by the radio signals transmitted from the instrument package and by other devices. Meteorologists are thus able to calculate wind direction and speeds at various altitudes in the atmosphere. The illustration on the left shows a wind profile with arrows to indicate direction. Notice how wind speeds vary and wind directions change. Occasionally, a band of air will be moving at a much higher rate of speed than adjacent air, as is illustrated in the wind profile on the right. The transition area is called a wind shear. A wind shear at 10,000 feet could have pronounced effects on a smoke convection column and its potential for long-range spotting.

Measuring Winds Measuring Winds

The measuring and predicting of general winds are usually beyond the capability of the firefighter in the field. He or she must rely on the meteorologist to provide this data and to interpret the effects of these winds near the surface.

The firefighter can observe and measure surface winds and, to some extent, should be able to anticipate changes in those winds. Under persisting atmospheric conditions, wind patterns can often be recognized, so that diurnal wind changes can be anticipated or predicted from day to day.

Copyright 2008, by the Contributing Authors. Cite/attribute Resource . admin. (2005, November 08). Unit 6: Local and General Winds. Retrieved January 07, 2011, from Free Online Course Materials — USU OpenCourseWare Web site: http://ocw.usu.edu/Forest__Range__and_Wildlife_Sciences/Wildland_Fire_Management_and_Planning/Unit_6__Local_and_General_Winds_4.html. This work is licensed under a Creative Commons License Creative Commons License