Meteorology Today, Ahrens Chap 7 Flashcards
what does it mean when a cloud droplet is in equilibrium with its environment
Water vapor evaporates and condenses at the same rate
What is Saturation vapor pressure
Total number of vapor molecules around the cloud droplet in equilibrium
Smaller cloud droplets have greater or smaller rate of evaporation
Greater, as curvature is larger compared to size of water droplet, more water vapor is needed to replace those that are lost
What is needed to keep a cloud droplet alive
Supersaturation, Relative Humidity is higher than 100% so water vapor constantly replenishes those that are evaporated.
What is curvature effect
Smaller cloud droplets require more Saturation vapor pressure to survive.
Relative humidity in a cloud does not typically grow more than what
101 Percent
What is the solute effect in clouds
when an impurity, such as salt, replaces a water molecule in the lattice structure of the droplet, the equilibrium vapor pressure surrounding the droplet is lowered.
As a droplet grows, what happens to solute effect
solute effect diminishes in effectiveness
Describe Collision Coalescence process
Cloud droplets collide with other cloud droplets
How can cloud droplets collide to undergo collision coalescence process
Falling droplets collide with others and Rising droplets collide with others(smaller droplets rise faster).
Is coalescence between 2 cloud droplets guaranteed if they collide
No, but those of opposite electrical charge are more likely to combine
What type of clouds maximize droplet growth
thick clouds with strong updrafts
In what type of clouds does the Collision coalescence process operate upon
Warm clouds, clouds that are above freezing at all altitudes
What is the glaciated region of a cloud
The region of the cloud that is completely composed of ice crystals
Are ice nuclei(nuclei that ice forms on) common in the atmosphere?
No
What is Graupel
ice crystals that have supercooled water that freezes on them.
Describe bergeron process
in a mixed-phase cloud where both ice crystals and supercooled water droplets exist, the ice crystals tend to grow larger at the expense of the surrounding water droplets, effectively “stealing” water vapor from them and causing the droplets to shrink or even evaporate completely. This is because the ice crystals take water vapor, which is replenished by the water droplets
What is sleet
When a falling snowflake falls through warmer air and melts but then falls through the deep
subfreezing surface layer of air, the partially melted snowflake
or cold raindrop turns back into ice, not as a snowflake, but as
a tiny ice pellet called sleet.
What is glaze
raindrops that reach the surface as supercooled liquid drop because it melts and the subfreezing surface layer of air is not deep enough to freeze the droplet.
What is Rime
small, supercooled cloud or fog droplets strike an object
whose temperature is below freezing, the tiny droplets freeze,
forming an accumulation of white or milky granular ice called
rime
