Dear Straight Dope:
What is the difference between hail, sleet, and freezing rain?
SDStaff Jillgat replies:
Let’s start with what they have in common: they all suck when you have a picnic planned. But so do muggy heat and mosquitos, so my solution is to live in New Mexico.
We do get hail in the southwest though, and there’s not much more fun than a good, sudden downpour of pinto bean size hail. I admit to some secret jealousy at never having experienced the baseball-size stuff. Tornadoes, too — I wanna see one of those.
I spoke to a weather guy who lives on my block (he can’t ever find a date … what’s wrong with women that they don’t appreciate a guy who knows his cumulonimbus?) and looked at this website . This is what I found out:
Freezing rain is supercooled rain that freezes when it hits cold surfaces. It is found on the cold side of a warm front, where the surface temperatures are at or just below freezing. Freezing rain can result in ice storms. We see these on the Weather Channel happening in other, less fortunate parts of the country. Freezing rain actually starts out as falling snow that hits a layer of warm air on the way down that causes it to melt and become rain. Then it passes through a thin layer of cold air that supercools it. When the drops strike frozen surfaces they freeze, forming a thin layer of ice.
Less common and more visible than freezing rain is sleet, which is frozen raindrops that bounce upon impact with a hard surface. Sleet happens on the coldest side (typically north) of a warm front, farther away from where freezing rain occurs. Sleet develops under very specialized atmospheric conditions, so is apparently difficult to forecast.
Hail is produced during intense thunderstorms. Water freezes onto snowflakes in the middle part of the cloud where there is an updraft, forming them into ice pellets. These pellets grow as more and more droplets are accumulated. Sometimes they reach the bottom of the cloud and are carried by the updraft back up to the top. When this happens, they pass through again and add another layer of ice. The stronger the updraft, the more times the hail stone repeats the cycle and the larger it grows before it falls to the ground as ice. I saw a lot full of new cars in Oklahoma once that were completely covered with dents and dimples from hail damage. Cool.
SDStaff Jillgat, Straight Dope Science Advisory Board
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