Precipitation Types

Types of Precipitation

1. Rain

2. Freezing rain

3. Sleet

4. Snow

5. Hail

In layered clouds with less intense updrafts, rain will fall at a fairly steady rate and raindrop sizes will be uniform
In a cumulonimbus cloud, there may be no rain in the updraft portion (updraft is stronger than the terminal velocity of rain), but very heavy rain in the downdraft

Rain: liquid water with diameters > 0.5mm
Drizzle: uniform drops of water < 0.5 mm
- - Fall from stratus cloud or partially evaporate from raindrops in dry air below cloud
Virga: rain or drizzle that falls from the cloud but evaporates before reaching the ground (see right top image)
Rain shower: a brief, sporadic rain event
Downburst: if the shower is excessively heavy (see right bottom image)

A snowflake melts as it falls
Goes through shallow freezing layer but not enough to form sleet
Then freezes on contact when it hits the cold ground, trees, cars, power lines, etc.

The temperature near the surface can affect the type of snowflake we see at the ground:
- - If it falls through warm air, it can start to melt, and the wet flakes can stick to each other to create “aggregates” – big fluffy flakes – good for snowballs
  - If it falls through cold, dry air, we get powder
If a snowflake melts before reaching the ground, it will form a raindrop
Most rain in the middle and northern latitudes began as snowflakes – even in the summer

Flurries: Snow falling from cumulus or stratocumulus clouds. These are light showers that fall intermittently for short periods. Only light accumulations or a dusting of snow is expected.
Snow Squall: A more intense snow show: brief but intense, similar to summer rain showers
Heavy Snow: 4 inches or more expected in the next 12 hours, or 6 inches or more expected in the next 24 hours

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