Precipitation Formation Mechanisms Questions and Answers

Answer: C

Correct answer: True

Where a montane forest stands in persistent cloud, droplets are intercepted by leaves and needles, coalesce and drip to the ground. In some cloud forests this occult precipitation contributes a substantial fraction of the annual water input - sometimes exceeding the measured rainfall - and a standard rain gauge in the open records almost none of it, which is why clearing such forest can reduce streamflow.

Answer: D

Radiative cooling of the surface below the dew point causes condensation in place. No cloud is involved and nothing falls, which is why it is not counted as precipitation. Its water still matters to surface energy and moisture budgets.

Answer: A

None of the four falls from a cloud in the usual sense, and all are classified separately from precipitation. They differ in whether the water arrives as vapour, as fog or as rain. Each produces a visually distinct deposit on the surface.

Answer: B

Both are true and the reason gives the distinction, and the feathery crystal shapes reflect that growth. Frozen dew produces rounded beads of ice with quite a different appearance. The crystal habit reveals which process was at work.

Answer: C

Correct answer: supercooled rain spreads before freezing on a surface

Glaze forms when supercooled raindrops land, spread out over the surface as liquid, and then freeze slowly enough that air escapes. The result is a dense, clear, tenacious coating that follows the shape of what it covers, and its weight is what brings down power lines and branches in an ice storm. Fast freezing of small droplets gives rime instead, and direct deposition of vapour gives hoar frost.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: slow freezing lets air escape and gives glaze its clear, dense structure, while the rapid freezing of individual droplets traps air and makes rime opaque and light. Statement 3 reverses the comparison - glaze is the denser and by far the more damaging of the two, precisely because it is solid ice rather than an aerated deposit.

Answer: A

Solid ice passes directly to vapour when the air is dry enough. In windy cold environments it can remove a substantial fraction of the snow that fell. Blowing snow greatly accelerates the loss. Snowpack budgets in polar regions must account for it.

Answer: B

Oceans cover some seventy per cent of the surface and evaporation over them is greater still. The sparseness of oceanic observations is why satellite measurement mattered so much. Ocean rainfall was long the least well observed component.

Answer: C

Correct answer: 2 - 4 - 1 - 3

Beginning with evaporation the order is forced. Water leaves the surface as vapour, condenses onto nuclei to form cloud droplets, grows by coalescence or through the ice phase into particles large enough to fall, and finally runs off and returns to the ocean. Each step needs the product of the one before it, so no other ordering is possible.

Answer: D

Dividing the atmospheric water content by the global precipitation rate gives roughly nine days. The short time reflects how rapidly the atmosphere cycles its comparatively small reservoir. The whole atmospheric store is replaced many times a year.