Level: K to H.S.
Time involvement: 20 to 30 min.
Courtesy of Green Bay NOAA weather station an actual weather balloon will be inflated to about 6 ft. diameter. Radiosonde and recovery parachute are included. (No helium or Hydrogen) A map of US launch sites will be shown. Launches occur twice a day simultaneously worldwide. Greenwich Mean Time (GMT) at midnight and noon are the release times. The radiosonde is the instrument collection device that sends data back to a ground station. Flights take 60-90 minutes and the balloon bursts at altitude of 10-12 miles. (Approximately 50K ft. to 60K ft.) Most important meteorological information is found below these altitudes. Collection and use of the data will be discussed. UW Madison is one of about 6 world archival sites for saving the data from balloon, satellites and ground stations.
Discussion: Weather forecasters use many ways to study the atmosphere from satellites, ground observations, radar signals, and balloons. The importance of predicting storms, tornadoes, freezing, climate change, etc., affect scientific, commercial, and governmental interests.
Learn more: As usual, the internet is an easy resource for information. The history of Radiosondes is shorter than the history of aviation but not by much.
See: http://en.wikipedia.org/wiki/Radiosonde. Not surprisingly some of the earliest radiosondes were experimental and merely encoded temperature data by Morse code. In the 1930s many nations began to realize the importance of weather forecasting for commercial, military, and scientific purposes and began programs of releasing radiosondes to aide forecasters. The essence of radiosonde data is that it not only must it be “fresh” and accurate but it is also important to know where the balloon is located. Since winds can carry the balloon a hundred miles or more during its ascent a means of getting a constant geographic fix to correlate with humidity, pressure, and temperature measurements is critically important.
The US government had been experimenting with satellites during the Cold war for intelligence and military purposes. In 1983 President Reagan directed that the GPS signals be made available for commercial purposes. Gradually, at first, aircraft and ground vehicles became equipped with GPS receivers. In 2005 the first regular use of GPS equipped radiosondes was begun. Today the equipment can be manufactured in very lightweight packages at affordable costs. Many nations participate in gathering and sharing upper atmosphere data which is saved at several archival locations around the globe, including UW Madison.
Notes: The balloon is very delicate. Students may be invited to touch it. A group photo of a dozen or more arms supporting the balloon makes a nice photo souvenir. With an electrical blower it takes several minutes to inflate and deflate the balloon. Students often show high interest in this unusual object. Presentation will be shorter for younger students.