Atmosphere: DGCA Aviation Meteorology questions

The atmosphere is layered by how temperature changes with height, and the International Standard Atmosphere, or ISA, is the agreed reference that altimeters and performance figures rest on.

Of the 45 questions, most are one word recall: layer names and heights, tropopause height by latitude, gas proportions, ozone, and where nacreous and noctilucent clouds sit. A few ask for an ISA deviation, worked by hand because no calculator is allowed in Meteorology. Exam sessions have used 24 of these.

ISA deviation is actual minus ISA, so air colder than standard gives a minus figure. Gas proportions by weight differ from those by volume, because an oxygen molecule is heavier than a nitrogen molecule.