cloud development and precipitation - II Flashcards
How do cloud droplets form?
through nucleation, when water vapor condenses into cloud nuclei and form cloud droplets
Is condensation an efficient way to make raindrops?
no
What is collision in terms of raindrop formation?
occurs in warm clouds, small cloud droplets join together through random collisions
What is coalescence in terms of raindrop formation?
occurs in warm clouds, large and faster moving cloud droplets overtake small and slower droplets
What impacts the size of raindrops?
clouds’ liquid water content, range of cloud droplet sizes, cloud thickness, updraft strengths, and droplets’ electrical charges
What is accretion in terms of precipitation formation?
occurs in cold clouds, ice crystals sweep up supercooled water drops and freezes them to the crystal on impact
What is aggregation in terms of precipitation formation?
occurs in cold clouds, ice crystals collide and form a singular larger ice particle
What is the WBF process?
the larger amount of water vapor particles surrounding water droplets transfer to ice crystals and cause the crystals to increase in size.
What determines an ice crystal/snowflake’s size?
how long it stays inside a cloud, the strength of updrafts, and the thickness of the cloud
What determines a snowflake’s form?
air temperature and humidity
What structures can a snowflake have?
plate, column, dendrite (most common form), and needle
What is freezing rain?
supercooled liquid that instantly freezes when it strikes a cold surface
What is sleet?
tiny, transparent ice pellets
How is freezing rain formed?
- snowflakes pass through a warm layer and melt
- the melted snowflakes reach a shallow freezing layer, causing them to drop in temperature and become supercooled
- when they hit a cold surface, they refreeze
How is sleet formed?
- snowflakes pass through a warm layer and melt into raindrops
- the raindrops reach a deep freezing layer and turn into sleet before reaching the ground
