Question

The frozen rain drops while falling through air at subfreezing temperature is known as

• A. Glaze
• B. Hail
• C. Sleet
• D. Snow

Hint:

Key distinction for exams:
- Freezes before hitting the ground \(\rightarrow\) Sleet.
- Freezes after hitting the ground \(\rightarrow\) Glaze (Freezing Rain).
- Layered ice formed in convective clouds \(\rightarrow\) Hail.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Precipitation occurs in various forms depending on the temperature profile of the atmosphere from the cloud level down to the ground.
These forms include rain, snow, hail, sleet, and glaze.

Step 2: Detailed Explanation:
Let us differentiate between the forms of frozen precipitation:
- Sleet (Ice Pellets): This occurs when raindrops falling from a warm layer of air aloft enter a deep, subfreezing layer of air near the Earth's surface.
The raindrops freeze into small, translucent ice pellets before hitting the ground.
Therefore, "frozen raindrops while falling through air at subfreezing temperature" is the exact definition of sleet.
- Glaze (Freezing Rain): This occurs when supercooled raindrops fall through a shallow cold layer and do not have time to freeze in the air.
Instead, they freeze instantly upon striking subfreezing surfaces on the ground, forming a smooth coating of ice.
- Hail: This is formed in strong convective clouds (cumulonimbus).
Violent updrafts carry water droplets repeatedly above the freezing level, causing them to freeze in layers.
This produces large, hard, concentric balls of ice (\(>5 \text{ mm}\)).
- Snow: This is formed by direct sublimation of water vapor into ice crystals at temperatures below freezing, forming flakes.

Step 3: Final Answer:
The frozen raindrops falling through subfreezing air is known as Sleet.