Hail or Sleet? There is a difference!

I have been a self proclaimed weather geek since i was probably eight years old. Every weather event interests me and i have gathered copious amounts of knowledge over the years on meteorology. This passion for a subject that impacts people all the time and is talked about on a basic level every day can be 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 produces hail include lots of moisture in the air, a strong updraft, and a high reaching storm system. This all means you need a tall thunderstorm, one that reaches high enough in the atmosphere for water droplets to freeze. So 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, other wise 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 can not 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.

Now onto sleet! Sleet occurs in a different situation and general in the winter season. Unlike hail which has to do with updrafts, sleet deals with different temperature layers in the atmosphere just above the ground. In a winter storm their is 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, that had fallen from a warmer layer above back into ice. So sleet pellets usually begin as snow and as they fall they hit a thick warm layer of air, causing them to melt into rain drops, 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. If so then you will make a weather geek's day when you use the term correctly because remember talking about the weather isn't just a filler conversation for weather nerds!