Evolution of Clouds Flashcards
Define Nucleation process
The action leading to the formation of the first new specks as a material begins to undergo a change of state at the boundary between to phases.
Describe the process of Natural Condensation
The process in which molecules of water vapor are brought together in sufficient numbers to form liquid water. It requires Supersaturations
What are Hygroscopic nuclei? and what are they composed of?
Nuclei that become impregnated with water before saturation of the air occurs. The are composed of water soluble substances.
What size are large nuclei?
0.1 to 1 micrometer
How long does it take a hygroscopic nuclei 1 micrometer in diameter to grow to a 1mm drop of rain?
3 hours
The process of cooling a water droplet’s temperature beyond its nominal freezing point is called:
Supercooling
At what temperature do all droplets freeze?
-41
Freezing occurs at much warmer temperatures than -41 because of:
Particles that act as freezing nuclei
The universal theory about freezing nuclei states that:
Certain condensation nuclei are a mixture consisting of hygroscopic substances and solid substances. thus, condensation takes place on the hygroscopic part and freezing takes place on the solid substance.
As the temperature lowers, the amount of freezing nuclei increases or decreases?
increases
List the 4 factors that control the evolution of clouds
- Water vapor
- Condensation and ice nuclei
- Stability
- Lift
For every 10 degrees the temperature increases, the amount of water vapor it can hold:
doubles
At temperatures below the freezing point, the ratio of the number of ice crystals to supercooled droplets ________ as the temperature _________
increases
decreases
The 4 types of vertical lift that assist in the formation of clouds are:
Large scale lift
Convection
Orographic lift
Mechanical turbulence
The two main processes that initiate convection in the atmosphere are:
Day time heating
Cold Air advection
What are the 3 key points of daytime heating:
Unequal heating of the earths surface
Surrounding air is colder than the parcel
small scale process
What are the 2 key points about CAA
Warmer surface below
Day or night
Intensity and altitude of mechanical turbulence depends on
roughness of the surface
Strength of the wind
inStability of the air
The cloud formed by mechanical turbulence will frequently be:
Stratocumulus unless the layer is very moist, then stratus.
there will always be an __________ at the top of the mixed layer
Inversion
With orographic lift, the extent of the cloud depends on ________ and the type of cloud depends on ________
The moisture of the air
The stability of the air
The cloud associated with lows and troughs and the fair weather associated with ridges and highs are due to:
Slow air mass decent or ascent caused by convergence or divergence.
The cloud produced by large scale vertical motion is generally:
Layered cloud. Cirrus, Altostratus or nimbostratus.
The process of break-up of an ice crystal into a large number of fragments is referred to as the:
fragmentation.
