State whether the following is true or false.
Mediterranean type climates occur on the western sides of continents in the subtropics.
Answer: D
California, central Chile, the Cape and southern Australia all show the pattern as well as the Mediterranean basin itself. The seasonal migration of the subtropical high is the common cause. Five regions share the pattern.
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Arrange the following in order from the equator polewards.
1. the mid-latitude rainfall maximum
2. the equatorial rainfall maximum
3. the polar desert
4. the subtropical dry belt
Answer: A
Correct answer: 2 - 4 - 1 - 3
The pattern follows the general circulation. Rising air at the intertropical convergence zone gives the equatorial maximum; the descending branch of the Hadley cell gives the subtropical dry belt around 20 to 30 degrees; the mid-latitude storm track gives a second maximum around 40 to 60; and the cold, dry, subsiding air over the poles gives the polar desert.
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State whether the following is true or false.
Polar regions receive very little precipitation despite their permanent snow cover.
Answer: B
Correct answer: True
Antarctic and high Arctic precipitation is a few tens to a couple of hundred millimetres a year - less than many hot deserts - because cold air can hold very little water vapour. The permanent snow cover reflects the fact that almost nothing melts or evaporates rather than that much falls, so the accumulation of thousands of years builds an ice sheet from a very small annual input.
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Consider the following statements about precipitation measurement.
1. Rain gauges undercatch in windy conditions.
2. Snowfall is harder to measure accurately than rain.
3. Radar measures rainfall directly and needs no calibration.
Answer: C
The first two are correct. The third is wrong, since radar measures reflected power and must be calibrated against gauges to give a rainfall figure. Wind is the main source of gauge error. Snow is harder still to catch reliably.
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Assertion (A): Rainfall radar is calibrated against surface gauges.
Reason (R): The radar measures the reflectivity of the drops rather than the rainfall itself.
Answer: D
Correct answer: Both A and R are true, and R is the correct explanation of A
Both are true and the reason gives the necessity. Radar measures reflectivity, which depends on the drop size distribution, and converting it to a rain rate requires a relationship that varies with the type of rain and with the height at which the beam samples. Gauges measure the rain reaching the ground at a point directly, so they anchor the radar’s excellent spatial coverage to a physical measurement - each supplying what the other lacks.
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The greatest annual rainfall totals in the world occur
Answer: A
Cherrapunji and the Hawaiian mountains are the standard examples, where orographic uplift acts on very moist air. The combination of moisture supply and forced ascent is what produces the extremes. Both factors must be present at once.
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State whether the following is true or false.
Global precipitation and evaporation must balance in the long term.
Answer: B
Water is conserved, so what falls must have evaporated, and the atmosphere holds only a few days worth of it. Regional imbalances are made up by the transport of vapour and the return flow of rivers. The atmosphere stores only days of it.
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