Definition
A small, expendable instrument package carried aloft by a weather balloon that measures temperature, humidity, and pressure as it rises through the atmosphere, and transmits those readings by radio to a ground receiving station. Wind speed and direction at altitude are derived by tracking the balloon's position during the ascent.
Plain English
A small box of weather sensors hung beneath a balloon that flies up through the atmosphere and radios temperature, moisture, and pressure readings back to the ground.
Context Anchor
Pilots encounter radiosonde data indirectly in weather products, especially forecasts and reports about upper-level temperature, moisture, and wind.
Derivation
From 'radio' (the transmission method) plus the French 'sonde,' meaning a probe or sounding device used to measure something at a distance — historically a line dropped from a ship to measure water depth. A radiosonde 'sounds' the atmosphere vertically and reports back by radio.
Why Pilots Care
Radiosonde data give pilots accurate upper-level wind, temperature, and stability information used for route selection and turbulence avoidance.
Grounding Statement
Picture a weather balloon rising through the sky while a small box underneath it sends back readings about the air at each height.
Intuition Check
A radiosonde is not just a radio. It is a weather probe that uses radio to send its measurements back to the ground.
Example Sentence 1
Twice a day, weather services release balloons carrying a radiosonde to gather temperature and wind data from the surface up to about 100,000 feet.
Example Sentence 2
Twice-daily radiosonde launches provide the vertical weather profile needed for accurate forecasts.