observation en altitude

OBS: observation en altitude : Observation météorologique effectuée dans l'atmosphère libre, soit directement, en aéronef par exemple, soit indirectement, au moyen d'un sondage exécuté à partir de la surface terrestre.
OBS: observations en altitude : terme normalisé au pluriel par l'ISO.

OBS: upper-air observation. This is a general term, but is usually applied to those observations that are used in the analysis of upper-air charts (as opposed to measurements of upper-atmospheric quantities primarily for research). Among the elements evaluated are pressure, temperature, relative humidity (e.g., by radiosonde aircraft observations), and wind speed and direction (e.g., by rawinsonde, aircraft, or wind profiling radars). Also, some mountain stations are high enough and exposed enough so that their observations may be included in the upper-air network at their elevation.
OBS: At each [weather] station, measurements are taken of such things as air pressure and temperature, wind speed, cloud cover, and precipitation. Elsewhere, upper-level observations are made by weather balloons, and satellites, which send a continuous flow of photographs back to earth.