Meteorology, like every other science, relies on careful and precise measurement of its subject. Weather observations are critical to both weather forecasters and computer models that predict the weather. These measurements are made at the ground level as well as in the atmosphere.
An important resource for weather observations near the ground is the Automated Surface Observing System, or ASOS (pronounced “A-sauce”).
There are about 2,000 ASOS stations located at airports across the country, and the instruments are maintained by the Federal Aviation Administration.
National Oceanic and Atmospheric Administration (NOAA) uses the Meteorological Assimilation Data Ingest System (MADIS) to collect and distribute weather observations from NOAA and non-NOAA organizations.
Meteorologists monitor the atmosphere above the surface by using a radio-equipped meteorological instrument package carried aloft by a helium-filled “weather balloon.”
These devices are launched twice a day by NOAA by over 100 locations across North America, the Pacific islands and the Caribbean. Radiosondes provide upper-air data that are essential for weather forecasts and research.
Weather observations of the upper atmosphere are also made by commercial aircraft flying passengers around the world and distributed to the National Weather Service to use in its computer models.
Satellites and radar systems provide a huge volume of observations.
Radar is used to track precipitating weather systems and are very valuable for short-term forecasts. Satellites track weather systems and make important observations for global weather prediction models.
Privately owned personal weather stations are also an important part of many private forecasting companies. Trained volunteers provide observations about precipitation and threatening weather conditions.