Wednesday, January 6, 2016

Name That Precipitation (Weather-related)

We're into that time of year where I'll overhear someone say, "Wow, it was hailing really hard last night!" and I'll mentally note that there were no thunderstorms in the area and it's really the wrong time of year for thunderstorms anyway.  Then I'll realize they're talking about sleet.  Totally different.

I'm rather saddened at how few people seem to know the difference between hail, sleet and freezing rain.  I do understand why it may be hard to keep them straight: all three are forms of precipitation that involve rain and ice, but all three are very unique and occur under very specific conditions. 

What saddens me more is that meteorologists - rather than educating the masses - are dumbing down their terminology.  Intellicast no longer uses the word "sleet" in its forecasts.  They now use the term "ice pellets".  Though this is indeed an accurate description of sleet, it does have a name and it's called "sleet".

So, what is the difference between the three?
Glad you asked for I'm here to answer!

Conditions - Typically warmer weather; more specifically during thunderstorms.

How's it made - Inside cumulonimbus clouds (the type that produce thunderstorms).
Hail starts as rain or small ice pellets that get kicked around within the towering cloud by wind.
The proto-hail gets thrown high up into the cloud where the air is colder and a layer of ice forms around it.  When it gets too heavy for the winds to hold it aloft it falls to a lower portion of the cloud just to get tossed up again for another coating of ice.
Once it's too heavy for a repeat trip upwards, it falls to the earth as an uneven blob of ice.

Hail can damage crops, vehicles, and structures.  Large hail can hurt people too.

A hail fall doesn't typically last too long and the hail itself tends to melt quickly as it usually occurs in the spring and summer months when the ground temperatures are rather warm.

Hail is an indication of severe weather and its presence can herald a tornado or intense thunderstorm.

Conditions - When surface air temperatures temperatures are below freezing, but temperatures aloft (in the clouds) are above freezing. 

How's it made - Sleet starts life in the clouds as rain.  As it falls to the earth it freezes into little ice pellets.  Unlike hail - which looks globular in nature and can be any size, sleet is evenly shaped and small (because it's just rain that turned to ice).

Sleet can fall with just as much intensity as rain and for as long as the temperatures are favorable for it to remain ice.  Sleet though can easily switch over to snow (if the air gets cold enough), or rain/freezing rain (if the air gets warmer).

Freezing Rain
Conditions - When the surface air temperatures are above freezing, but the ground and surfaces touching the ground are below freezing.

How's it made - Freezing rain is liquid rain that...well, freezes as soon as it hits something.
This forms a smooth, even coating of ice on trees, cars, the ground, anything it lands on because those surfaces are colder than the air that's just warm enough to keep it liquid.

This ice build-up can bring down power lines or cause tree limbs to fall across power lines, causing power outages.  The smooth ice can also accumulate on roads making travel difficult.

So those are the three types of frozen precipitation that tend to get mixed up or used interchangeably.
Hopefully this guide will help you keep them straight so that you too can use the correct descriptions for what's falling from the sky.

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