Is it Hail or Sleet? There is a difference!
Extreme Hail Storm
I have been a self proclaimed weather geek since the age of eight! Every weather event interests me and I have gathered copious amounts of knowledge over the years on meteorology. My passion for a subject that impacts people at every living moment but is talked about on a basic level every day can become frustrating when terms are used incorrectly. One of my biggest pet peeves about conversations revolving around meteorology is the misuse or confusion of the terms sleet and hail. Many believe that because hail and sleet both hit the ground as chunks of ice that they are synonymous. Well they are NOT! Below i'll briefly describe how both hail and sleet are formed and conclude with how they are different.
Lets take a quick look at hail. Hail is normally found in thunderstorms, which can happen all year long but are more frequent in the spring and summer months. The ingredients needed to produce hail includes lots of moisture in the air, a strong updraft, and a towering vertical storm system. The thunderstorm has to reach high enough in the atmosphere for water droplets to freeze.
Hail is formed during the process of a thunderstorm when air is being pulled up into the center of the storm. Remember hot air rises and cold air sinks, so when the ground heats up in the summer, it creates enough instability to cause storms to pop up. These strong winds up from the ground in storms are called updrafts. These updrafts carry water droplets up, as long as they don't get too heavy, otherwise they fall as rain. As the updraft carries the water droplets up to colder part of the clouds they begin to freeze and stick together, forming a piece of ice. Now to determine how large the hail becomes depends on how strong the updraft is to hold the ice up in the clouds. Once the ice accumulates to a size that cannot be supported by the updraft it falls to earth as hail. This is why hail comes in different sizes and shapes. The diagram to the right shows the life cycle of hail.
Jim Cantore Explains Hail
Now onto sleet! Sleet occurs in a different situation than hail and is generally associated with the winter season. Unlike hail which is a result of updrafts, sleet deals with different temperature layers in the atmosphere just above the ground.
In a winter storm there are four different precipitation types that you can get: snow, rain, sleet, or freezing rain. All of these types are determined by the layering of cold and warm air just above the surface. If all layers are cold you get snow, if all layers warm you get rain, but it gets a bit more tricky when it comes to sleet and freezing rain. Freezing rain has a warm level of air just above the surface, however the last 10 meters or even less (sometimes just the ground) is below freezing, causing rain to freeze on contact. When you have sleet that last layer near the ground is just big enough and cold enough to freeze rain which is falling from a slightly warmer layer above back into ice.
So sleet pellets usually begin as snow and as they fall they hit a thick layer of warm air, causing them to melt into raindrops, then before hitting the ground, the drops fall through a cold layer just thick enough to freeze the rain back into ice. See the diagram below for an illustration.
So what makes hail and sleet different?
- Hail is created by updrafts
- Sleet is created by cold and warm layering of air
- Hail is found in thunderstorms
- Sleet is found in winter storms
- Hail can be a variety of sizes and shapes depending on the updraft
- Sleet is generally the same small pellet
I hope this hub has helped you to understand the differences between hail and sleet. Hopefully this knowledge will help you will make a weather geek's day when you use the term correctly! Remember talking about the weather isn't just a filler conversation for weather nerds!