27 practice questions on Pressure Systems & Depressions with answers and explanations, plus the key concepts and formulas, from the TrueHeading question bank.
Use this page to revise Pressure Systems & Depressions for the DGCA Aviation Meteorology paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 27 questions in the TrueHeading bank for this topic.
In short: Low: air converges and rises, cloud and rain, anticlockwise in the northern hemisphere. High: air sinks and diverges, clear skies, clockwise.
Open the full set in the student zone to answer every question, track your accuracy and take timed mock tests.
3 ideas to know cold.
Low: air converges and rises, cloud and rain, anticlockwise in the northern hemisphere. High: air sinks and diverges, clear skies, clockwise.
A wave forms on the polar front, deepens, and the faster cold front overtakes the warm front to make an occlusion.
Northern hemisphere: clockwise around a high, anticlockwise around a low (opposite in the southern hemisphere).
Tap “Show answer” after you have tried each one.
Answer: B. anticlockwise and inwards (towards the centre)
Friction turns the wind across the isobars toward low pressure.
Answer: D. clockwise and outwards
Air spirals clockwise and outward around an anticyclone in the NH.
Answer: B. clockwise
The Coriolis force is reversed.
Answer: D. strong winds
The pressure gradient force is strong, and the geostrophic wind is proportional to the gradient.
Answer: C. on your left
Back to the wind, low pressure is on the left in the northern hemisphere.
Answer: D. settled, stable weather
Subsidence dries and stabilises the air.
Answer: D. the region between two highs and two lows with light, variable winds
A col is a saddle point; fog and thunderstorms may form there.
Answer: C. converging and rising
Surface convergence produces ascent, cloud and precipitation.
Answer: C. sinking (subsiding)
Subsidence suppresses cloud.
Answer: A. from west to east, steered by the upper winds
Mid-latitude depressions are carried by the westerlies.
Answer: D. between the warm front and the cold front
Warm tropical air lies in the sector between the two fronts at the surface.
Answer: B. cold front catches up with the warm front
The cold front moves faster than the warm front and lifts the warm sector off the ground.
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