| Focus 3/3 | Thunderstorms: electricity in the air

Instruments for observing thunderstorms


Weather conditions associated with thunderstorms can be monitored by ground-based instruments, such as rain gauges to measure rainfall. The internal structure of thunderstorms can be observed using ground-based weather radars. Rain drops and ice crystals backscatter the radio waves transmitted by the radar, which then, through scanning, provides a two- or three-dimensional picture of the internal structure of the thunderstorms (Figures a and b). Depending on the wavelength used, droplets, drops or crystals of different sizes can be distinguished. For in-situ analyses, aircraft can be equipped with measuring instruments. They can image different kinds of hydrometeors which are then analyzed to determine their characteristics and spatial distribution. On a larger scale, thunderstorms can be tracked by satellite (Figure c). For example, infrared images can be used to identify the coldest areas, corresponding to the highest clouds and therefore to cumulonimbus clouds and their anvils (Figure d). Radars can also be carried on board satellites. Thus, the Cloudsat satellite makes it possible to document the three-dimensional structure of convective systems in a global way (Figures e and f).

Encyclopédie environnement - orages - instruments d'observation
Photographs of the various thunderstorm observation instruments and examples of the storm images they provide.
a) The Massachusetts Institute of Technology (MIT) radar located in Niamey, Niger [Source: © Sandrine Bony].
b) View of a grain line by the MIT radar [Source: © Earle Williams].
c) A meteorological observation satellite of the European Space Agency, Meteosat [Source: © ESA, D. Ducros].
d) View of grain lines through the infrared channel of the Meteosat satellite [Source: © Eumesat].
e) The Cloudsat observation satellite [Source: © NASA].
f) View of a cyclone through the Cloudsat satellite [Source: © CloudSat DPC, NASA].