Articles

The Precipitation Radar was the first spaceborne instrument designed to provide three-dimensional maps of storm structure. These measurements yield invaluable information on the intensity and distribution of the rain, on the rain type, on the storm depth and on the height at which the snow melts into rain. The estimates of the heat released into the atmosphere at different heights based on these measurements can be used to improve models of the global atmospheric circulation. The Precipitation Radar has a horizontal resolution at the ground of about 3.1 miles (five kilometers) and a swath...

The Tropical Rainfall Measuring Mission’s (TRMM) Microwave Imager (TMI) is a passive microwave sensor designed to provide quantitative rainfall information over a wide swath under the TRMM satellite. By carefully measuring the minute amounts of microwave energy emitted by the Earth and its atmosphere, TMI is able to quantify the water vapor, the cloud water, and the rainfall intensity in the atmosphere. It is a relatively small instrument that consumes little power. This, combined with the wide swath and the good, quantitative information regarding rainfall make TMI the "workhorse" of the rain...

The Visible and Infrared Scanner (VIRS) is one of the primary instruments aboard the Tropical Rainfall Measuring Mission (TRMM) observatory. VIRS is one of the three instruments in the rain-measuring package and serves as a very indirect indicator of rainfall. It also ties in TRMM measurements with other measurements that are made routinely using the meteorological Polar Orbiting Environmental Satellites POES) and those that are made using the Geostationary Operational Environmental Satellites (GOES) operated by the United States. VIRS, as its name implies, senses radiation coming up from the...

High in the atmosphere, water collects on dust and smoke particles in clouds. Raindrops start to form in a roughly spherical structure due to the surface tension of water. This surface tension is the "skin" of a body of water that makes the molecules stick together. The cause is the weak hydrogen bonds that occur between water molecules. On smaller raindrops, the surface tension is stronger than in larger drops. The reason is the flow of air around the drop. As the raindrop falls, it lose that rounded shape. The raindrop becomes more like the top half of a hamburger bun. Flattened on the...

Problem-Based Classroom Modules A series of PDF files which provide full classroom lessons and problem sets for a number of precipitation-related topics. The Shape of a Raindrop A lesson on what causes raindrops in our atmosphere to be a certain shape. Create a Sphere with Precipitation Climatology Click above to download the PDF file. This is an activity in which students will cut and fold paper to create a 3D sphere which displays the precipitation climatology (long-term average) computed by the Global Energy and Water Experiment for 1979-2008. This activity was created by Dr. Chris Kidd and...