Upperair

Upper air, in meteorology, refers to the portion of the Earth’s atmosphere above the near-surface layer where weather typically forms. It encompasses the upper troposphere and the stratosphere, and is studied to understand vertical structure, stability, wind shear, and large-scale circulation. Observations of the upper air provide critical information for diagnosing weather patterns and for forecasting beyond what surface observations alone can reveal.

The primary source of upper-air data is radiosondes carried aloft by weather balloons. As the balloon ascends, instruments measure temperature, humidity, pressure, and wind, producing vertical profiles called soundings. Other methods supplement radiosondes, including aircraft-based observations, lidar and radar wind profiling, satellite sounders, and microwave radiometers. Satellite instruments can infer temperature, moisture, ozone, and wind fields for layers that are not easily sampled by balloons.

Upper-air data are essential for numerical weather prediction models, used to initialize forecasts and to assess atmospheric stability, jet streams, tropopause height, and stratosphere-troposphere interactions. They also support climate research and weather climatologies. Programs and archives operated by meteorological agencies and the World Meteorological Organization collect and quality-control upper-air observations, such as radiosonde networks and integrated global archives.

Limitations include uneven geographic coverage (notably over oceans and remote regions), instrumentation biases, and delays in data transmission. Ongoing improvements focus on higher-resolution, more frequent observations and better calibration to enhance model performance.