Why does hail reach the ground smaller and less often in the tropics than in mid-latitudes?
Show answer & explanation
Answer: Hailstones there melt on the long fall through warm air
Storm clouds there are too shallow to reach freezing air — Tropical thunderclouds are among the tallest on Earth, not too shallow. The ceiling that caps storm clouds sits about 17 km up near the equator, against roughly 9 km near the poles, so the upper parts of these clouds are far below freezing and do make ice.
Hailstones there melt on the long fall through warm air ✓ — In the tropics the air stays above freezing up to roughly 4.5 km or higher, so a hailstone faces a long, warm, humid fall before it reaches the ground. Small stones melt fastest, because they fall slowly and expose a lot of surface for their size, so most arrive tiny or as cold rain. That is why tropical hail is seen mainly in high places such as Bogotá, where the ground lies closer to the freezing air.
Hailstones there find too little cloud water to grow — Tropical air is some of the most humid on Earth, so growing hailstones have plenty of cloud water to feed on. The moisture actually works against hail on the way down, because stones melt faster falling through damp air than through dry air.
More Weather & Climate questions
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- Why do hail researchers simulate the paths individual hailstones take through a storm instead of just counting how many thunderstorms occur?
- Why can one hailstone have both clear and cloudy ice layers instead of growing in one simple up-and-down path?
- Why is the coldest storm top not the best place for hail to grow?
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- In a warming climate, how can fewer small hailstones reach the ground while the largest hailstones become more common?