China Civil UAV Theory Questions — Questions 611–620

The higher the pressure, the lower the density. The atmosphere is bound by Earth's gravity; with increasing height, Earth's gravitational pull on the atmosphere weakens, so air molecules diffuse more easily and density falls. Simple memory: under gravity, plateau air is thin and low-density. Plateaus lack oxygen.

Wind direction 180 degrees is a south wind (from due south); taking off and landing into the wind is best, so the direction is from north to south.

An air mass is a large air mass with horizontally uniform meteorological elements (temperature, humidity, and similar), with little internal weather variation.

Different air masses differ greatly in meteorological elements; a sharp temperature and wind direction change within a short time indicates entry into another air mass.

Cumulonimbus tops are smooth with neat edges, appearing white on satellite images, matching the description; cumulus groups and mid-level clouds lack this feature.

Meteorological conditions inside an air mass are stable and change little, so option B is correct.

On the north side of a high-pressure system and the south side of a low-pressure system, airflow deflected by the Coriolis force turns from a south wind into a west wind, matching the west-to-east flight direction and forming a tailwind.

On the south side of a high-pressure system and the north side of a low-pressure system, airflow deflected by the Coriolis force turns from a north wind into an east wind, matching the east-to-west flight direction and forming a tailwind.

In the Northern Hemisphere, flying from high to low pressure, airflow deflected right by the Coriolis force comes from the aircraft's left: a left crosswind.

In a Northern Hemisphere low-pressure area, air converges toward the center and, deflected right by the Coriolis force, forms counterclockwise inward rotation.