Ice Nucleation and Ice Crystal Growth Questions and Answers

Answer: C

The first two are correct and are the substance of the habit diagram. The third is contradicted by laboratory work, in which habit changes reproducibly as conditions are varied. The habit diagram is one of the most robust results in the field.

Answer: D

The accreted droplets freeze almost instantly and coat the crystal in opaque rime. Heavy riming eventually obscures the original habit and produces graupel instead. Riming is the route by which a crystal becomes a dense pellet.

Answer: A

Both are true and the reason gives the process, and continued riming converts the particle into graupel. The original habit becomes impossible to identify once riming is advanced. Degree of riming is itself used as an observational classification.

Answer: B

A quasi liquid layer near the melting point helps colliding crystals adhere. Dendritic interlocking near minus fifteen provides a second and quite separate aggregation maximum. The two maxima arise from entirely different surface behaviour.

Answer: C

The first two are correct and identify the two maxima. The third is wrong, since aggregation is notably inefficient in the intermediate range where crystals are compact and not sticky. Aggregation efficiency is therefore strongly temperature dependent.

Answer: D

The sequence corresponds broadly to increasing residence time in a mixed phase cloud. Which type reaches the ground depends on the profile of temperature and liquid water it fell through. The particle records the profile it descended through.

Answer: A

Graupel is soft rimed ice a few millimetres across, whereas hail is dense and can be much larger. The distinction is conventional but reflects genuinely different growth conditions. Graupel forms in modest updraughts and hail in violent ones.

Answer: B

The stone must remain in the supercooled liquid region long enough to accrete a large mass. Updraught strength is the principal control on the maximum hail size a storm can produce. Hail size is used operationally as a proxy for updraught strength.

Answer: C

Both are true and the reason gives the requirement, and terminal velocity rises with size so the updraught must strengthen too. Hail size is therefore used as an indicator of storm severity. Reports of large hail are treated as evidence of a severe storm.

Answer: D

The sequence describes how most mid-latitude rainfall actually forms. Rain at the surface in temperate regions has usually passed through the ice phase on its way down. Warm rain contributes only a small share outside the tropics.