Upper Air Observations

Cross Sections of the Atmosphere

This is where we launch one of our most important weather instrument, the weather balloon and rawinsonde. Its purpose is to rise through the atmosphere, and gather a vertical cross section of weather information, including the temperature, dewpoint, and wind direction and speed, at different pressure levels of the atmposphere. Inside the dome of the Upper Air Building is a dish that receives radio signals. This dish locks onto the signal of the 'sonde in order to receive it's data. The instrument also has onboard GPS. By seeing changes instrument's location we are able to find out the wind speed and direction aloft. Inflating the Balloon Intern Casey Dail Releases the Balloon Balloon in Flight

Data Data Everywhere

The readings received by the rawinsonde are plotted for a meteorologist to examine. These vertical cross sections are plotted on what is referred to as Skew-T Log-P diagram. Among the many uses that meteorologists have for the Skew-T Log-P is the determination of the stability of the atmosphere and the potential for severe weather. Many other meteorological parameters can be analyzed from the data collected by weather balloons. We launch balloons twice a day under normal conditions, and in bad weather situations, such as when a hurricane approaches the area, up to four times a day. At over 100 sites across the country, the National Weather Service launches balloons. In fact balloons are launched all across the globe, at the same time twice a day. All this information is then collected at the National Center for Environmental Prediction (NCEP) and used as input for the numerical computer models which meteorologists use to make their forecasts. In addition, the high level data collected by these instruments are of use to the aviation industry. Skew-T Log-P Example

What Happens When it Bursts?

When a weather balloon with attached rawindsonde reaches a certain point in the atmosphere (normally 10 millibars) the balloon pops. The pressure difference between the balloon and the atmosphere at that level can expand the size of a balloon to larger than a 2 story house! When it does pop, the attached parachute brings the rawinsonde safely down to the ground. If a rawindsonde is found, the individual that finds it is encouraged to mail the device back to us using the prepaid return envelope included with each 'sonde. Each rawinsonde returns saves the US taxpayers money. If the 'sonde is not found, it is designed to biodegrade as much as possible, however the styrofoam body of the 'sonde is not able to break down. Hopefully one day a different material can be used so that all components of the 'sonde will biodegrade. Picture of a Rawinsonde After Return