Why is hail formed in this portion of the cloud?
Choose one or more:
A. Updrafts keep particles higher in the cloud.
B. Temperatures are just right to allow water to melt and then refreeze into balls.
C. Temperatures are low enough in the cloud to melt any ice particles that form.
D. Temperatures are low enough to supercool water droplets.
Answer (1)
Hail forms in thunderstorms under specific conditions involving air movement and temperature within the cloud. Here's how each of the options relates to hail formation:
(A) Updrafts keep particles higher in the cloud.
This option is accurate. In thunderstorms, strong updrafts (rising air currents) help lift water droplets to higher altitudes in the cloud where temperatures are colder. These updrafts repeatedly carry the droplets upwards, allowing them to encounter vast areas of cold air. It is in these higher parts of the cloud that these droplets begin to freeze into hailstones. As long as the updraft is strong enough to support their weight, they remain suspended and can gather more layers of ice until they fall as hail.
(B) Temperatures are just right to allow water to melt and then refreeze into balls.
This option is somewhat accurate. Although the main process of hail formation does not involve melting and refreezing, temperatures within the cloud must be conducive to allowing supercooled droplets (liquid water below freezing point) to freeze onto the hailstone. Upon being carried upwards by the updraft, droplets collide with the nascent hailstone, freezing upon contact and adding another layer of ice.
(C) Temperatures are low enough in the cloud to melt any ice particles that form.
This option is incorrect. Hail formation requires low temperatures to freeze supercooled water droplets and grow ice layers around the hailstone. If temperatures in the cloud were warm enough to melt the ice, hail would not form.
(D) Temperatures are low enough to supercool water droplets.
This option is accurate. Within the cloud, temperatures are low enough to cool water droplets below freezing point without turning them into ice immediately. These supercooled droplets are crucial for hail formation, as they freeze upon contact with forming hailstones, allowing the hailstone to grow in size with each upward travel.
Therefore, the correct options for why hail forms in this portion of the cloud are (A) and (D). Hail formation relies on the combination of strong updrafts to keep particles high in the cloud and low temperatures to provide the conditions for supercooling and freezing water droplets.
