Answer:
Troposphere is the lowest most layer of Earth's atmosphere. The mean height of troposphere from the surface are 18 km in tropical regions, 17 km in middle latitudes, and 6 km in polar regions.
There exists an inversion layer called as tropopause, which acts as border between troposphere and stratosphere. The air temperature keeps on decreasing as we go high in the tropopause but remains constant throughout its thickness.
Usually, scientists use weather balloon as an instrument to take measurements in the upper troposphere.
Weather balloon also known as sounding balloon is a balloon that carries the measuring device (known as radiosonde) with it to the intended heights and stays there for long duration. The device then obtains all the measurements such as atmospheric pressure, temperature, wind speed, humidity etc and send them back to the scientists.
In addition, scientists may compare these data with those obtained from other means such as aircraft data and satellite data.
