These two forms of precipitation occur under very different circumstances.
Although hail and sleet are somewhat similar, they actually occur in completely different weather and require completely different environments to form. So, what’s the difference? First, let’s talk about hail.
How does hail form?
Hail usually forms during summer thunderstorms. Raindrops form at the base of clouds during thunderstorms. Updrafts during severe storms cause these raindrops to be carried from the bottom of the cloud to the top of the cloud, where temperatures are significantly cooler. This cooled water freezes when it comes in contact with ice crystals, dust or other matter and forms a small hailstone.
It then falls to the bottom of the cloud, only to be lifted up again by the updraft. It would come into contact with colder water, causing another layer of ice to form around the hailstone. The hailstones eventually fall to the ground when the updraft weakens or the hailstones become too heavy to stay in the clouds and gravity pulls them toward the earth.
Like trees, the annual rings of hailstones are also of great significance. If you take a piece of hailstone and slice it, you should be able to tell from the number of layers it has been brought to the top of the storm.
The hailstones range in size from the size of a pea to the size of a softball. On June 23, 2010, the largest piece of hailstone recorded in the United States fell on Vivian, South Dakota, measuring 8 inches in diameter and 18.62 inches in circumference. It weighs 1 lb 15 oz.
In 1986, the world’s heaviest hailstone, weighing 2.25 pounds, fell on Bangladesh, where hailstones often come before the summer monsoon season. Not surprisingly, hail can cause extreme damage.
Although Florida is the state with the most thunderstorms, hail is most likely to occur in Nebraska, Wyoming and Colorado. In fact, the area where the three states meet is known as “Hail Alley” and averages seven to nine days of hail a year.
How does sleet form?< /em>
One major difference to understand between hail and sleet is the time of year. Hail occurs in warm weather, generally during thunderstorms in spring, summer and fall, while sleet occurs only in colder weather.
When temperatures drop below 32 degrees Fahrenheit (zero Celsius), precipitation that falls from clouds turns into snow. As this snow falls from the warmer atmosphere, it melts slightly and then turns into pucks of ice as it passes through cooler regions, allowing it to hit Earth as sleet.
This has been described as a “warm air sandwich,” where precipitation starts out cold at high altitude, warms up, and then freezes again. This is the same phenomenon that causes freezing rain, unlike snow, which travels through the atmosphere at a constant low temperature.
Unlike hail, sleet is small and falls from the sky only once. When it hits the windshield or the ground, it makes a fair amount of noise, but doesn’t do as much damage as hailstones. The accumulation of sleet on roads and sidewalks can be dangerous, but it’s not the most dangerous form of winter weather. Generally, projectiles simply bounce off the surface they touch. In some cases, the sleet can even provide the driver with a little traction — though that shouldn’t be a reason to go faster in inclement conditions.
Where is the freezing rain?< /strong>
Freezing rain is worse than sleet when it comes to safety. This winter precipitation falls as snow, like sleet, that melts when it hits a warmer layer of air. However, this warm layer is deeper than in the case of sleet, and the particles do not have time to refreeze before hitting the ground. When it hits the Earth’s surface — where the temperature is below 32 degrees — it also freezes. Since freezing rain only freezes when it hits roads and sidewalks, it looks dangerous. It looks like it’s raining, but turns the ground into a dangerous skating rink. You have to be very careful when you walk and drive.