Which one of the following statement with reference to hailstones is NOT correct?

Correct — A, their formation usually occurs during the monsoon season. This is the statement that fails, and a 'NOT correct' stem asks for exactly that. Hail needs a deep convective cloud with very strong updraughts and a thick subfreezing layer, and in India those conditions are found chiefly in the pre-monsoon months of March to May and in association with winter western disturbances over the north — the same season that brings the norwesters of eastern India. During the monsoon proper the atmosphere is moist through a great depth and the freezing level is high, so rainfall is heavy but hail is uncommon. The other three statements are each standard descriptions of hail, which leaves this one as the answer.

• (b)They are associated with dense cumulonimbus clouds — Hail is indeed associated with dense cumulonimbus. Only that cloud has updraughts strong enough to hold an ice pellet aloft while it grows, which is why cumulonimbus is the only hail-producing cloud type.
• (c)Rain that forms in the warmer, upper layer solidifies into tiny ice pellets or hailstones in the lower, subfreezing layer — This sentence reproduces the standard textbook account of freezing precipitation, where drops formed in a warm layer aloft solidify in a subfreezing layer below. It is printed in physical geography texts in almost these words, so the examiner has treated it as correct.
• (d)Hailstones have multiple, concentric layers of ice — Hailstones do have concentric layers of ice, alternately clear and opaque, built up as the stone is carried repeatedly through wet and dry growth zones. Cutting one open and counting the layers is the classic demonstration.

Hail forms inside a cumulonimbus with a powerful updraught. An ice particle is carried up into the subfreezing part of the cloud, collects supercooled water that freezes onto it, falls, is caught by the updraught and lifted again. Each passage adds a layer, alternately clear where freezing is slow and opaque where trapped air bubbles are included, so the finished stone has an onion structure. The stone falls when it grows too heavy for the updraught, which is why stronger storms produce larger hail.

Three of the four statements describe the physics of hail and only one makes a claim about season, which is the signal that the seasonal claim is where the item is decided. For India the association to hold is hail with the pre-monsoon thunderstorm season, not with the rains — hailstorms damaging standing rabi crops in Madhya Pradesh, Maharashtra and the north are a March-April news item, not a July one. Option (c) is the one worth a second thought, because as written it describes the formation of sleet more accurately than of hail; but it is a sentence lifted from standard texts, and the seasonal error in (a) is the clearer failure.

• Hail forms in cumulonimbus clouds with strong updraughts that carry ice particles repeatedly through subfreezing layers.
• A hailstone has concentric layers of ice, alternately clear and opaque, one for each passage.
• In India hail is chiefly a pre-monsoon and winter phenomenon, associated with thunderstorms and western disturbances.
• Norwesters of eastern India, called kalbaisakhi in Bengal, are pre-monsoon thunderstorms that can bring hail.
• A hailstone falls when its weight exceeds what the updraught can support, so stronger storms give larger stones.

• Assuming that because the monsoon brings the heaviest rain it must also bring the hail.
• Treating hail as a form of frozen rain rather than as a product of repeated updraught cycling.
• Associating hail with any large cloud rather than specifically with cumulonimbus.

A 'which is NOT correct' item where three statements describe mechanism and one makes a seasonal claim. The odd statement out by type is the one to examine.

• practice — not a real PYQ

  Hailstorms in India are most common during which season?

  • (a)The south-west monsoon
  • (b)The pre-monsoon months of March to May
  • (c)The retreating monsoon
  • (d)The peak of summer over the Thar Desert

  Answer(b) The pre-monsoon months of March to May — the season of intense local thunderstorms.

• practice — not a real PYQ

  Which cloud type is associated with thunder, lightning and hail?

  • (a)Cirrus
  • (b)Stratus
  • (c)Cumulonimbus
  • (d)Altostratus

  Answer(c) Cumulonimbus — the only cloud with updraughts strong enough to build hailstones.