1. Types of precipitation
List 9 forms of precipitation:

2. Essential Question: How do different types of precipitation form?
Rain, drizzle, mist
Snow
Sleet
Freezing rain or glaze
Hail
Rime, graupel
Temperature Profiles

4. The type of Precipitation depends on the Temperature Profile of the atmosphere.

5. Temp. Profile for __________
Below freezing
Above freezing
-20°C °C °C

8. Snow
Crystals

10. Formation of Sleet

11. Rain freezes too close to the ground to have enough time to turn to snow.

12. Glaze Sleet Falls as __________ On the ground as __________________

13. Rime
Starts as _________
On surfaces as ____________
Frost
Starts as _________
On surfaces as ____________

14. What if the rain never reaches the ground?
Virga: rain evaporates before it hits the ground in desert regions
“rain curtain”

15. Formation of
Hail

16. Hailstone
Cross section
Hail
Damage

17. Text book page 496

18. Precipitation Measurement

19. Rain gauge
with
metal slats to
minimize
“under-catch” in
windy
conditions

20. TRUE / FALSE
Snowflakes are 6-sided crystals
There is such a thing as ‘heart-attack’ snow
It cannot snow if it’s too cold.
Skiers love ‘powder’ snow

21. Snow Fall Measuring Using a measuring stick in several locations.
“1 inch of rain equals 10 inches of snow”
But, the quantity of water
in snow varies…
It depends on the
temperature profile.

22. WET SNOW - Wet snow is snow that has a high liquid content as it reaches the surface.
It needs to be at least 50% made of ice or it will have more characteristics of being a raindrop instead of a snowflake.
It gets this liquid content by partially melting before it hits the ground.
The wetness of the snowflakes makes it easier for snowflakes to stick together as they fall, thus a wet snow will often have large snowflakes and a lower number of snowflakes
The ratio for wet snow will be less than 10:1. For example, it takes 10 inches of snow to produce 1 inch of liquid equivalent.

23. DRY SNOW- A dry snow has little to no liquid water content thus this snow will be less dense than average, there will be a lot of air pockets between the snow crystals.
Dry snow is not sticky (it’s powdery) and thus it is difficult to make snowballs with it and the wind blows it around even after reaching the surface.
The ratio for dry snow will be greater than 10:1. In extreme cases it can be 30:1 or greater.
Dry snow occurs when the temperatures throughout the troposphere are well below freezing and the surface temperature is below freezing.
Since dry snowflakes are less sticky they are less inclined to stick together as they fall, thus a dry snow will often be composed of a large number of small snowflakes.

24. Measuring Snow Equivalent
Fill a 100 ml graduated cylinder with “snow” _______inches
Record the outdoor temperature ________ °C
Find the outdoor humidity for that day ______ %
Allow all the water melt. Record the volume. ______ inches
Calculate the snow: water ratio ________ :_______
reduce to ______: 1

25. warm
COLD!

27. Doppler Radar Display

28. Weather Modification Cloud Seeding Fog Dispersal Hail Suppression
Frost Prevention

29. Cloud
Seeding
Cloud
Dispersal

30. Hail Suppression
Hail Cannon

31. Frost Suppression
Wind
Machines
Orchard
Heaters
Sprinklers

32. Role of Clouds in the Climate System