Simple balloons make computers look good
One of the tools meteorologists use on a daily basis to forecast the weather are computers.
Using equations based on the laws of physics, powerful computers perform millions of calculations that result in an output of variables such as temperature, pressure, humidity, and wind speed that can be plotted on a map and analyzed.
To get this kind of output, however, the computer must first start with some input. The input consists of data gathered from nearly 900 weather balloons launched at the same time, twice a day, 365 days a year, across the globe. Of those, about 69 are launched from National Weather Service offices across the conterminous United States. Locally, the Spokane National Weather Service office launches its weather balloon daily at 4 a.m. and 4 p.m. PST, shifting to 5 a.m. and 5 p.m. during daylight saving time.
Attached to these weather balloons, which are filled with hydrogen or helium, are radiosondes – small expendable instrument packages that can measure atmospheric variables such as temperature, pressure, and relative humidity and transmit this information back via a battery powered radio. By tracking the position of the radiosonde in flight, information on wind speed and direction aloft can also be obtained.
The flight of these weather balloons can last more than two hours. During that time, the balloon can ascend nearly 20 miles and drift more than 125 miles from the release point. As the air pressure decreases with increasing altitude, the balloon expands (can grow as large as a two-car garage) and eventually bursts. With the help of a small parachute, the instrument, which weighs about a pound, makes it back down to the ground.
What happens once they hit the ground? Well, only about 20 percent of the approximately 75,000 radiosondes released by the National Weather Service are returned – to be reconditioned and used again (saving taxpayer dollars). If you should ever stumble upon a National Weather Service radiosonde, it is safe to handle and even comes with a postage paid plastic mailbag inside to allow you to easily return the instrument.
Assuming the radiosonde was not severely mangled on landing, it merely looks like a rectangular styrofoam box, clearly labeled as a radiosonde, and may still have a deflated balloon attached to it along with an orange parachute.
The upcoming week looks to be wet and slightly warmer than average, which should once again result in more rain than snow for valley locations. Snow amounts for both Spokane and Coeur d’Alene so far are still running about half of average for the season.