China Civil UAV Theory Questions — Questions 621–630

Study note: inward, upward, counterclockwise. In a Northern Hemisphere low-pressure area, air converges inward from all sides, rises, and rotates counterclockwise under the Coriolis force.

Study note: a downwind turn is easily blown outward into a wider turn. In a downwind left turn, wind pushes the UAV so it travels farther during the turn, making a wider turn.

A cold air mass moving over a warm surface is heated from below and rises, forming cumulus clouds, strong turbulence, and good visibility.

Study note: airspeed, altitude, vertical speed, pitch. Wind shear causes abnormal changes in airspeed, altitude, vertical speed, and pitch angle, so these four instruments can identify it; fuel gauges and wind speed indicators do not directly reflect wind shear.

A front is the interface between cold and warm air masses, and temperature difference is its most significant feature.

A mature cyclone (such as a typhoon) appears as a spiral cloud system on visible-light images, its typical feature.

In summer, when a warm air mass is unstable, vigorous convection in a cold front's stratiform cloud system can produce cumulonimbus (thunderstorms).

Study note: for the international standard atmosphere, look for sea level. The international standard atmosphere indeed uses sea level as the pressure reference and defines temperature, pressure, and other parameters at different heights. Sea level is chosen as the reference because it is one of the most universal and widespread level surfaces on Earth; with vast oceans, sea level height is relatively consistent everywhere, making it a very stable and reliable reference.

Study note: when you see violent vertical convection, choose it directly. Stratospheric characteristics: temperature rises with height or stays roughly constant; airflow is stable with almost no vertical motion; little surface influence, with regular temperature and humidity distribution. “Violent vertical air convection” is a tropospheric characteristic.

The entire stratosphere has almost no vertical air motion, with stable airflow. Option A is wrong (there is still a tiny amount of water vapor); option C is wrong (temperature rises with height).