24 NC counties are under alert, including Wake, Cumberland, Johnston, Wayne, and Harnett counties. Details
Wake County manager Jim Hartmann to retire in October — Wake County Manager Jim Hartmann announced on Thursday that he will be stepping down from his role at the end of October. Hartmann has served as county manager for 3.5 years.
Published: 2008-11-08 13:00:47
Updated: 2008-11-08 13:00:47
Posted November 8, 2008
MIKE MOSS SAYS: Brittany, Meteorologists definitely use balloons, and lots of them, in order to help characterize the state of the atmosphere in order to do analysis of weather patterns and to obtain data for initializing computer forecast models.
The most common and most important balloon is a radiosonde, sometimes called a rawinsonde. The National Weather Service launches these twice a day from about 92 sites in U.S. territory, and other organizations and countries are responsible for about 900 other sites around the world. These balloons measure temperature, humidity, pressure and wind speed/direction from near the surface up to about 80-90,000 feet above the ground and send the data back to receivers on the ground by way of radio telemetry.
There are some other balloons that are launched somewhat less frequently but can be locally very important. A "pilot balloon" can be launched from the surface and tracked with an instrument called a theodolite that measures elevation and azimuth angles that allow wind direction and speed to be calculated without the use of a radio, using principles of trigonometry. In addition, pilot balloons can serve as ceiling balloons, by following the balloon until it becomes obscured by a cloud base, and then calculating the height of that cloud base by way of knowledge of the time involved and the rate of ascent of the balloon.
There are also some other more specialized balloons, such as the "jimsphere" used by NASA to collect high altitude, high-resolution wind profiles in support of rocket and shuttle launches, and radar calibration balloons that are used to insure weather radars are tuned properly.