What is the difference between sleet and drizzle

You can get help with updating your browser here. One of our Weather Watchers in Cumbria wrote in recently to ask us to explain the difference between several types of precipitation. You'll often see terms such as 'drizzle', 'light rain' or 'heavy snow' in the forecast, but how are these terms differentiated from each other?

To answer this, we'll start with defining what exactly is meant by the term 'precipitation'. Precipitation is any form of water solid or liquid falling from the sky. Liquid water falling from the sky is of course most often called rain but how is this different from drizzle?

It's down to the size of the droplets. If the water droplets are smaller than 0. Whether rain is termed light, moderate or heavy is not down to the size of the droplets but to the intensity at which it falls. Light rain has an intensity of less than 0. Sleet and freezing rain form because of a "warm-air sandwich" in the atmosphere above our heads. Precipitation starts as snow in the cold layer at the top, then melts to rain as it falls through the warm layer, then refreezes into sleet or freezing rain as it falls through the cold layer near the surface.

For sleet to occur, the warm air layer is rather thin. A thicker wedge of cold air beneath the warm air refreezes the partially melted snow into ice pellets.

For freezing rain to occur, the warm air layer is thicker. The snow melts into rain then refreezes just as it hits the cold ground. Since the rain is not freezing until it reaches the surface, it still falls like regular rain and therefore looks and feels the same until it freezes on the ground. Sleet is made up of ice pellets that bounce off objects. Even though this may sound more hazardous than freezing rain, that's not the case.

Finally, when the air is warm enough all the way down to the surface, it's just plain rain that reaches down here. While sleet and hail are both forms of frozen precipitation, they form in completely different ways and often at different times of year.

Sleet forms in winter storms, while hail is a warm-season type of precipitation. As noted above, sleet forms when snow melts in a warm layer and then refreezes into ice pellets as it falls though a cold layer. Hail, however, forms in spring, summer or fall thunderstorms. First, soft, snow-like particles form in subfreezing air at the top of a thunderstorm. Yes, even in the middle of summer, the tops of thunderstorms are below freezing.