Precipitation requires above all that air be
Answer: A
Rising air expands and cools, and condensation follows once saturation is reached. Every precipitation mechanism is essentially a way of making air rise. Expansion does the cooling. Saturation is reached as the parcel rises.
Please log in or register to report this question.
Match each uplift mechanism with the precipitation it produces.
List I
A. Convective
B. Orographic
C. Frontal
D. Convergent
List II
1. widespread moderate rain along a boundary
2. showers and thunderstorms, often intense and local
3. the persistent rainfall of the ITCZ
4. heavy rain on the windward slope of a range
Answer: B
Correct answer: A-2, B-4, C-1, D-3
Each mechanism lifts air in a different way and the rainfall reflects it. Convection lifts a narrow column rapidly, giving intense local showers and thunderstorms. Orographic lifting is forced by terrain and concentrates heavy rain on the windward slope. A front lifts a deep layer gently over a long boundary, giving widespread moderate rain. And large-scale convergence sustains the persistent rainfall of the intertropical convergence zone.
Please log in or register to report this question.
The equatorial belt of heavy rainfall is associated with
Answer: C
Converging trade winds force air upward and the deep convection produces year round rainfall. The zone migrates north and south with the sun through the year. Converging trades force the ascent. Rainfall there is high through the whole year.
Please log in or register to report this question.
Assertion (A): The great deserts of the world lie near twenty to thirty degrees latitude.
Reason (R): Air descends in the subtropical high pressure belt, warming and drying as it sinks.
Answer: D
Both are true and the reason gives the mechanism: subsiding air cannot produce precipitation, and the Sahara, Arabian and Australian deserts all lie in that belt. Descent suppresses rain entirely. The belt shifts with the seasons.
Please log in or register to report this question.
Consider the following statements about the latitudinal rainfall pattern.
1. A maximum lies near the equator.
2. Minima lie near twenty to thirty degrees in each hemisphere.
3. Rainfall increases steadily from equator to pole.
Answer: A
The first two are correct and give the characteristic double-peaked pattern. The third is quite wrong, and the secondary maximum in mid-latitudes is followed by a decline towards the polar deserts. Two minima and two maxima make the pattern.
Please log in or register to report this question.
A rain shadow forms
Answer: B
Air that has lost its moisture ascending the windward slope warms as it descends. The contrast across a range can be a factor of ten in annual rainfall. Descent warms and dries the air. Windward and lee sides can differ tenfold.
Please log in or register to report this question.
Assertion (A): The lee side of a mountain range is drier than the windward side.
Reason (R): Air descending the lee slope warms and its relative humidity falls.
Answer: C
Both are true and the reason gives the mechanism, and the effect is strengthened because much of the moisture has already been removed on the way up. Two effects work in the same direction. Moisture loss and warming both dry the air.
Please log in or register to report this question.
Air at 20 degrees rises 2 kilometres, saturating and cooling at 6 degrees per kilometre, then descends the far side at 10 degrees per kilometre. What is its temperature on arrival?
Answer: D
It cools twelve degrees going up and warms twenty coming down, so it arrives eight degrees warmer than it started. This is the foehn effect and it explains why lee slopes are both drier and warmer. Latent heat release is the reason.
Please log in or register to report this question.
The foehn or chinook wind is
Answer: A
Correct answer: a warm dry wind descending a lee slope
Air that has been lifted over a range, cooled at the saturated rate and precipitated its moisture then descends the far side warming at the *dry* rate, so it arrives warmer and much drier than it began. That asymmetry is what makes the foehn and the chinook remarkable - temperature rises of twenty degrees in an hour are recorded - and it is the mechanism that produces a rain shadow.
Please log in or register to report this question.
A monsoon climate is characterised by
Answer: B
Differential heating between land and ocean drives the reversal, and the summer onshore flow brings the rain. South and East Asia have the best developed examples but the pattern occurs elsewhere. Land and sea heat at different rates.
Please log in or register to report this question.
