Q. How long have satellites been used to study Earth's weather?

A. The first successful meteorological experiment conducted from a satellite was launched on Explorer VII on Oct. 13, 1959, fifty years ago Tuesday.

Explorer VII carried an instrument that measured Earth's heat balance. The thermal radiation experiment was devised by UW-Madison Professor Verner E. Suomi, along with his colleague from the College of Engineering, Professor Robert J. Parent.

The instrument measured the balance between incoming solar radiation to the atmosphere and the radiation exiting the atmosphere as a result of reflection and emission processes. The energy budget drives weather patterns of the globe and is therefore an important component of climate. Those early measurements of the net radiation by Suomi and Parent have fostered 50 years of investigations into Earth's energy balance. This type of observation continues today and is planned for the next 20 years.

Today, we take for granted the bird's-eye view of developing weather systems that satellites provide. Forecasters use these orbiters to monitor shifting weather systems including thunderstorms, hurricanes, and extratropical cyclones. And, thanks to the Web, anyone can access quality satellite images with just a few mouse clicks. Today, more than 120 U.S. space-based instruments observe our planet. Future satellite systems in development will help improve our ability to monitor climate change and forecast storms.

For more information, see http://www.ssec.wisc.edu/media/spotlight/explorer7.html.

- Steven A. Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA Radio (970 AM) the last Monday of each month at 11:45 a.m.

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