17 January 2011

Retrieving radiosondes and rawinsondes

This morning I learned the proper name for a weather balloon:
Q: How are temperatures in the higher atmosphere measured?

A: Meteorologists monitor the atmosphere above the surface by using a radio-equipped meteorological instrument package - called radiosondes - carried aloft by a helium-filled weather balloon. The radiosondes measure vertical profiles of air temperature, relative humidity and pressure from the ground all the way up to about 19 miles. Temperature and relative humidity are measured electronically; a small aneroid barometer measures pressure.

Wind speed and direction can also be determined by tracking the position of the balloon. When winds are also measured, the observation is called a rawinsonde.
Even more interesting was a question I'd always wondered about:  How do meteorolosits get all that equipment back?
At low air pressures in the stratosphere, the balloon expands so much that it explodes and the radiosonde drifts back to the ground underneath a small parachute.
You learn something every day.

("Sonde" is French for "probe.")  Text from the Wisconsin State Journal.  Image credit NOAA.


  1. and how do they avoid aircraft?
    is there airspace restriction to do that?

  2. I don't know. And I wonder how they avoid parachuting the equipment onto an interstate highway at rush hour.


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