China Civil UAV Theory Questions — Questions 531–540
Unofficial study reference only. Not affiliated with or endorsed by any civil aviation authority — the official syllabus and regulations prevail.
UAV-Q0531. A parcel of air at some altitude in the atmosphere, when acted on by an external force and displaced upward or downward, is in a stable state when:
Explanation
Stable state: after moving, air decelerates and tends to return to its original height. Unstable state: it accelerates. Neutral state: it continues moving at constant speed.
UAV-Q0532. A wind barb shaped like “F” with two equally long barbs represents
Explanation
Study note: “Four”. In a wind barb “F”, each barb represents force 2 winds; two barbs mean force 4 winds.
UAV-Q0533. From isobars analyzed on a surface weather chart, we can observe:
Explanation
The spacing of isobars indicates pressure gradient magnitude: the denser the isobars, the greater the pressure gradient, reflecting how sharply pressure changes.
UAV-Q0534. Thunderstorms are produced by strong cumulonimbus clouds. Forming strong cumulonimbus requires three conditions: ______
Explanation
The three conditions for forming strong cumulonimbus (thunderstorms) are a deep, distinctly unstable air layer, abundant water vapor, and sufficient lifting force.
UAV-Q0535. When an aircraft flies in air colder than the standard atmosphere, the pressure altimeter's indicated altitude will be ______ the actual flight altitude.
Explanation
Cold air is dense with a large vertical pressure gradient, so the altimeter reads high: indicated altitude is higher than actual altitude.
UAV-Q0536. What is the correct method for classifying air masses?
Explanation
Study note: when two short options and one long option appear, choose the longest. Air masses are classified by source region into Arctic Ocean, polar, tropical, and equatorial air masses; options A and B mix classification dimensions and are incorrect.
UAV-Q0537. On satellite cloud images, which of the following is NOT a cirriform cloud characteristic?
Explanation
Study note: when you see “fibrous”, choose it. A fibrous structure is a typical cirrus characteristic, so option B's description is incorrect.
UAV-Q0538. Wind shear airflow often plunges rapidly from high altitude like a giant faucet pouring downward. When an aircraft enters this area:
Explanation
When wind shear airflow plunges and spreads outward, the aircraft first encounters a strong headwind, enters the downdraft zone, and then encounters a strong tailwind.
UAV-Q0539. Ground terrain and large buildings will:
Explanation
Ground terrain and buildings scatter wind direction, producing gusts that change direction and speed rapidly.
UAV-Q0540. Regarding aircraft icing, which is correct?
Explanation
Aircraft icing mostly occurs at 0 to −20°C, with the most encounters at −2 to −10°C, and severe icing mainly at −2 to −8°C.