Precipitation

Question 1

Describe the Bergeron theory of rainfall development

Answer 1

• Saturation vapour pressure decreases with decrease in temperature.
• Saturation vapour pressure decreases even more below 0degrees as ice formation requires lower pressure
• Below 0degrees, the air becomes saturated for the formation of ice before it becomes saturated for the formation of water.
• Ice particles grow by sublimation, at the expense of water droplets

Question 2

Describe the Coalescence theory of rainfall development.

Answer 2

• Larger droplets mix with smaller droplets growing in size.
• Once they are large enough they fall as drizzle/rain

Question 3

List the factors that affect the fall rate of water droplets.

Answer 3

• Gravity
• Larger water droplets fall faster than small water droplets
• Speed of updrafts/downdrafts