Weather Quiz

Characteristics of a moist, unstable air mass include cumuliform clouds, showery precipitation, rough air (turbulence), and good visibility (except in blowing obstructions).

All altimeter settings are corrected to sea level. Unequal heating of the Earth's surface causes pressure differences.

The wind is reported as a five-digit group (six digits if speed is over 99 knots). The first three digits is the direction the wind is blowing from rounded to the nearest tens of degrees relative to true (not magnetic) north, or "VRB" if the direction is variable. The next two digits is the speed in knots, or if over 99 knots, the next three digits. If the wind is gusty, it is reported as a "G" after the speed followed by the highest gust reported. The abbreviation "KT" is appended to denote the use of knots for wind speed. The wind group for KJFK is 18004KT which means the wind is from 180 degrees at 4 knots.

Downdrafts characterize the dissipating stage of the thunderstorm cell and the storm dies rapidly.Answer (A) is incorrect because updrafts occur during the cumulus stage. Answer (C) is incorrect because both updrafts and downdrafts occur during the mature stage.

Thermals are updrafts in convective currents dependent on solar heating. A temperature inversion would result in stable air with very little, if any, convective activity.