ROANOKE, Va. (WFXR) — Are you a weather fan or an expert? See if you can correctly guess this WFXR Weather Trivia question!

On a typical day, how many weather balloons are launched by an individual National Weather Service (NWS) office?

Attached to weather balloons are radiosondes, which are used to collect information on the temperature, humidity, pressure, and winds aloft. Since the late 1930s, NWS has taken upper air observations with radiosondes.

Every day, twice a day, weather balloons are launched simultaneously from some 900 stations around the world. For example, NWS Blacksburg launches at 7 a.m. and 7 p.m. EDT or 6 a.m. and 6 p.m. EST.

NWS offices can conduct extra balloon launches during periods of severe weather or winter weather.

According to the NWS, balloon flights can last around two hours. Weather balloons can drift as far as 125 miles away and rise up to more than 20 miles in the atmosphere.

Upper-air data is used for a number of forecasts and research. The information is used for weather prediction models; local severe storm, aviation, and marine forecasts; weather and climate change research; and as input for air pollution models.