Our Radiosonde Makes a Surprise Landing in Albuquerque!


Motorists and residents near the intersection of San Pedro and Candelaria in Albuquerque's northeast heights received quite a surprise on July 11th, 2007, when an unidentified object fell from the sky and onto a car. A small case with wires and a plastic parachute with a warning message resulted in some apprehension and Albuquerque Police including the bomb squad were called to the site.

The "unidentified object" was actually a "weather balloon" and an instrument called a radiosonde released that evening from our office. The balloon was launched near the airport around 5:00 pm MST. Our sensors indicate that the balloon "burst" one and a half hours after release at an elevation of 95,000 feet. Thirty minutes later, around 7:00 pm, the ruptured balloon, instrument case, and parachute landed just a few miles from where it was released!

Radiosondes are instruments used to measure weather parameters at elevations up to 100,000 feet. An expendable instrument package (the white box above) is about the size of a shoe box and contains sensors that measure temperature, humidity, and air pressure. The package is attached to a balloon filled with hydrogen (hence the warning tag in case the balloon is found still inflated) and released. By tracking the position of the instrument, wind speed and direction is obtained. A parachute is used to slow the descent of the package as it falls back to the surface. Our office releases a radiosonde twice each day. The balloons can travel more than 100 miles from the launch site and it is quite rare for the package to end up in the Albuquerque Metro Area.
   
While we use a parachute to reduce the descent speed and minimize danger to lives and property, we also hope to minimize damage to the instrument package. Once on the ground, if the instrument is found,directions for returning the radiosonde to the National Weather Service are listed on a side of the case. About 20 percent of the radiosondes launched are returned in this manner. On the evening of July 11th, this side of the case was face down when the radiosonde came to rest on the sidewalk.
   
The data obtained from the radiosonde is used to produce a sounding, or a plot of the meteorological conditions from the surface to 100 mb, or about 50,000 feet. The sounding from this event is shown below. Soundings are routinely used by our forecasters to evaluate the state of the atmosphere and are particularly useful when forecasting severe weather. However, the "upper air" data obtained through the radiosonde program are also very important input for our weather and climate forecast models. Soundings are always available from our web site, under the "Skew-T Diagrams" heading on our observations page.
   
   

More information on the upper air program and radiosondes is available at the following sites:

Jetstream On-line Weather School
The NWS Upper Air Program
NOAA's 200 Years Celebration


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