Orographic precipitation is primarily caused by
- AConvection due to intense solar heating of the ground
- BThe meeting of warm and cold air fronts
- CThe forced upward movement of moist air over a mountain barrierCorrect
- DThe movement of air from a high-pressure to a low-pressure area
Solution
Concept
Orographic lifting mechanism of precipitation
Formula
NONE
Step-by-step solution
1. Orographic precipitation occurs when a moisture-bearing air stream encounters a topographic barrier such as a mountain ridge. 2. The barrier forces the air to lift mechanically along the windward slope. 3. As the air ascends, it cools adiabatically, reaches saturation, and precipitates moisture heavily on the windward side. 4. Hence, orographic precipitation is caused by the forced upward movement of moist air over a mountain barrier. Answer: C
Explanation
Orographic precipitation occurs when a moisture-laden air mass is physically forced to ascend over an elevated topographic barrier such as a mountain range. The forced mechanical lifting causes the air to expand adiabatically, cool below its dew point, condense, and deposit precipitation on the windward slope, creating a rain-shadow zone on the leeward slope.
Why the other options are wrong
A) Intense solar heating generates convective updrafts that cause convective precipitation, such as summer storms. B) Meeting of air fronts causes cyclonic or frontal precipitation. D) Air moving from high to low pressure drives horizontal winds, not vertical lifting.
Shortcut
Orographic rain = Forced mechanical uplift of moist air over mountain barrier -> Adiabatic cooling & precipitation.
Common mistake
Confusing orographic rainfall (topographic lift) with convective rainfall (solar thermal uplift) or cyclonic rainfall.
Correct answer: C) The forced upward movement of moist air over a mountain barrier