Sleet

Definition

Sleet is a type of precipitation that occurs when rain droplets freeze into ice pellets before reaching the ground. This weather phenomenon typically happens during winter storms, where warm air layers aloft allow precipitation to fall as rain, but colder air near the surface causes the raindrops to freeze into ice pellets.

5 Must Know Facts For Your Next Test

1. Sleet forms when raindrops pass through a layer of cold air, which cools them enough to freeze into small ice pellets before they hit the ground.
2. The temperature profile in the atmosphere is crucial for sleet formation; it requires a layer of warm air above a cold layer near the surface.
3. Sleet can cause slippery conditions on roads and sidewalks, similar to snow and freezing rain, posing risks for transportation.
4. Unlike snowflakes that accumulate softly, sleet pellets are denser and can create a hard crust on surfaces, leading to challenges for snow removal.
5. Sleet is often confused with hail, but unlike hailstones, which form during thunderstorms, sleet occurs during winter weather events.

Review Questions

• How does the atmospheric temperature profile influence the formation of sleet?
  • The formation of sleet is highly dependent on the atmospheric temperature profile. For sleet to occur, warm air must exist above a colder layer. When precipitation starts as rain in the warm air aloft and then moves through the cold layer near the surface, it freezes into ice pellets before reaching the ground. If the entire column of air is below freezing, snow would form instead.
• Compare and contrast sleet with freezing rain and snow in terms of their formation processes and impacts.
  • Sleet, freezing rain, and snow all involve different atmospheric conditions and processes. Sleet forms when rain freezes before hitting the ground due to a cold layer at the surface, resulting in ice pellets. In contrast, freezing rain falls as liquid but freezes upon contact with surfaces, creating dangerous ice layers. Snow forms as ice crystals that fall when temperatures are consistently below freezing throughout the atmosphere. Each type of precipitation affects travel and infrastructure differently; while sleet creates slippery surfaces like snow does, freezing rain poses significant hazards due to its ability to coat objects with a thick layer of ice.
• Evaluate the potential impacts of sleet on urban infrastructure during winter storms and discuss strategies to mitigate these effects.
  • Sleet can significantly impact urban infrastructure by creating slippery roads and hazardous walking conditions, potentially leading to accidents and injuries. Additionally, accumulated sleet can cause damage to trees and power lines due to its weight. To mitigate these effects, cities can implement proactive measures such as pre-treating roads with salt or brine solutions before storms occur, conducting regular monitoring and clearing of streets post-storm, and educating residents about safe travel practices during icy conditions.

Related terms

Freezing Rain: Precipitation that falls as rain but freezes upon contact with cold surfaces, forming a glaze of ice.

Snow: Frozen precipitation in the form of flakes that fall from clouds when temperatures are below freezing.

Ice Storm: A significant weather event characterized by the accumulation of ice from freezing rain, often causing hazardous conditions.