China Civil UAV Theory Questions — Questions 591–600
Unofficial study reference only. Not affiliated with or endorsed by any civil aviation authority — the official syllabus and regulations prevail.
UAV-Q0591. When a thunderstorm is in its developing stage
Explanation
In a thunderstorm's developing stage (cumulus stage), air rises and surface pressure keeps falling.
UAV-Q0592. The stratosphere extends from the tropopause to about 55 km, and air heat comes mainly from ozone absorbing solar ultraviolet radiation. Therefore:
Explanation
Ozone in the stratosphere absorbs large amounts of solar ultraviolet radiation, so temperature rises with height.
UAV-Q0593. In practical use, the temperature lapse rate is usually expressed in units of:
Explanation
The lapse rate is defined as the temperature decrease per 100 meters of height gain, in °C/100 m. The tropospheric average lapse rate is 0.65°C/100 m. The 100-meter unit is more practical for calculation; a 1000-meter scale is too coarse.
UAV-Q0594. In meteorology, wind direction means
Explanation
In meteorology, wind direction means the direction wind comes from; for example, a northwest wind blows from the northwest.
UAV-Q0595. The effect of temperature on an aircraft's maximum level flight speed is:
Explanation
At low temperatures, air density is high and engine thrust increases (more intake air), raising maximum level flight speed; the drag increase has a weaker effect.
UAV-Q0596. When flying at low altitude in valleys, ridges, or mountains, turbulence danger is most likely encountered when ( )
Explanation
When flying downwind on a mountain's leeward side, the wind direction and terrain-created speed gradient are large, easily producing strong turbulence.
UAV-Q0597. Thunderstorms greatly endanger aircraft. Which hazard is NOT accurate?
Explanation
Thunderstorms cause lightning, hail, wind shear, turbulence, and other hazards; data link interruption is not a typical thunderstorm hazard.
UAV-Q0598. In meteorology, an air layer with a vertical temperature lapse rate of zero (γ = 0) is called
Explanation
Study note: when you see an equals sign, look for isothermal. An isothermal layer is one where temperature does not change with height (γ = 0); an inversion layer is one where temperature rises with height (γ < 0).
UAV-Q0599. Internationally, which visibility definitions are correct?
Explanation
Smoke visibility is less than 1 km; mist is 1–2 km; haze is 2–5 km, so option A is correct.
UAV-Q0600. In meteorology, visibility is expressed as meteorological optical range. Meteorological optical range means:
Explanation
Meteorological optical range is the path length over which a parallel light beam of color temperature 2700 K from an incandescent lamp is attenuated to 5% of its initial luminous flux.