Which weather instrument is typically carried into the atmosphere by a weather balloon to observe and report meteorological conditions from the upper atmosphere?

• A. A device that measures wind speed high in the atmosphere.
• B. A ground-based weather radar used for precipitation.
• C. A device for recording humidity at sea level.
• D. A weather instrument that observes and reports meteorological conditions from the upper atmosphere, typically carried by a weather balloon.

Answer: (D)

The thing being tested is upper‑air observation with a radiosonde carried by a weather balloon. A radiosonde is a small payload that carries sensors for temperature, humidity, and pressure, and it often includes a radio transmitter (and usually a GPS receiver) to report those measurements back to the ground as the balloon ascends. By tracking the balloon’s path with the transmitted data, meteorologists obtain a vertical profile of the atmosphere—temperature, humidity, and pressure—with altitude. This information, collected up to the balloon’s burst altitude (roughly 20 to 30 kilometers, about 65,000 to 100,000 feet), is essential for understanding conditions high above the surface and for forecasting. The other options describe instruments or uses not carried by balloons to observe the upper atmosphere: ground-based radar isn’t carried aloft, humidity sensors aren’t measuring upper-atmosphere conditions, and while wind data can be obtained from the radiosonde system, the key instrument for upper-atmosphere observations is the radiosonde itself.