403.3 - composition and formation of precipitation

Precipitation is all types of moisture reaching ____ from the atmosphere. Droplets must grow to ______ the size of cloud droplets to form precipitation.

the earth, 100 times

Precipitation is any product of the ______ of atmospheric water vapour, which is deposited on the earth’s surface.

condensation/sublimation

The type of precipitation encountered is partially determined by the form of _____ in the cloud.

the moisture particles

In Canada, due to the cooler climate, virtually all precipitation begins as ice crystals.

Cloud particles can grow by two methods, _____, or _____.

the ice crystal process, the collision process

The ice crystal process is also known as ______.

the Bergeron process

The Bergeron process occurs when air reaches saturation and some of the resulting droplets come into contact with _______ (assuming they have reached the activation temperature). The air is now a combination of _____ and _____.

freezing nuclei, ice crystals, supercooled water droplets

From the perspective of the supercooled droplets , the air is ______ at saturation. From the perspective of the ice crystals, the air is _______.

in equilibrium, supersaturated

Water vapour will sublimate on the ice crystals. Because ________ has decreased, and from the perspective of the supercooled water droplet, the air is _______, the supercooled water will evaporate until the air once again reaches saturation. This process continues.

the amount of water vapour in the air, below saturation

Summarize the Bergeron process.

The ice crystals grow through sublimation at the expense of the supercooled water droplets.

In the collision process (aka _____), the falling ice crystals may or may not melt during descent but can grow by colliding with ______, the larger ones tending to capture the smaller ones that lie in their path.

coalescence, other crystals of various sizes

What can cause the different particles to collide and assists in the growth of precipitation by carrying water vapour and droplets to higher altitudes?

Strong vertical air currents

The stronger the vertical currents, ______ the cloud tops and ______ to form large precipitation size particles.

the higher, the better the chance of collisions

Unstable conditions forming _______ will give the biggest raindrops, snow flakes and hail.

cumuliform type clouds (ACC, TCU, CB)

The two processes (ice crystal and collision) will be enhanced if ______, and therefore the biggest precipitation particles are formed in cumuliform type cloud.

there is a lot of mixing in the air

The ice crystal process occurs in a cloud composed of two things. What are they?

Supercooled water droplets and ice crystals

What is the name of the process by which rain drops grows in size or volume?

The collision process, or coalescence

High cirriform clouds do not precipitate because there is little moisture due to what?

Very cold temperatures

How are ice pellets formed?

By the freezing of rain drops

Which type of cloud can produce intermittent precipitation, SC or TCU?

SC

What two types of clouds does freezing rain fall from?

NS and AS

Heavy continuous snow can fall from which of the following clouds? CU, NS, thick ST or thick AS

NS and thick AS