Which instrument observes and reports meteorological conditions from the upper atmosphere, typically carried by a weather balloon?

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

Answer: (D)

In weather observations, an instrument that observes conditions high in the atmosphere and is typically carried by a weather balloon is the radiosonde package. It carries sensors for temperature, humidity, and air pressure, and usually includes a wind-measuring capability (often from GPS-based tracking) to determine wind speed and direction. As the balloon ascends, the radiosonde sends back data to ground stations, creating a vertical profile of the atmosphere from near the surface up through the upper layers. This is exactly what the described option refers to: an instrument that observes and reports meteorological conditions from the upper atmosphere, typically carried by a weather balloon. The other choices describe equipment that remains on the ground or measures surface conditions, or uses ground-based radar for storm tracking, none of which provide upper-atmosphere data via a balloon payload.