Cloud Formation

What Are Clouds A consequence of the evaporation of water followed by condensation of water droplets during the water cycle

3 Ways Clouds are Formed Convective clouds – form as a result of evaporation of water which rises into the atmosphere as air near the Earth's surface is heated. – As the air rises, it expands and cools. – This results in condensation of microscopic particles of water (about one-millionth the size of a normal drop of water). – These condensed particles of water form convective clouds.

Frontal clouds – form when a warm air mass meets a cooler air mass. – Since warm air masses are generally less dense than cooler air masses, the warm air mass tends to move above the cooler air mass. – As the warm air mass rises above the cooler air mass, frontal clouds form due to the expansion and resulting cooling of the air.

Orographic clouds – form as warm air masses move up the sides of a mountain. – As the warm air rises it expands and cools resulting in the formation of orographic clouds as water vapour condenses into microscopic droplets of water.

Fog Fog is actually a cloud formed at or near ground level. Fog may be formed as warm air moves over cold land masses, over snow fields, or cold bodies of water. Fog may also form as a result of orographic lifting.

Questions – p The hydrosphere is all of the earths water, including salt and freshwater, ice, and water vapor 2.Because we cannot use saltwater for drinking or agriculture 3.It is important to learn about saltwater because it covers the majority of the earths surface, and it affects weather because it contributes to such factors as clouds, precipitation and fog.

4. A glacier “grows” with every snowfall and becomes compressed with every snowfall, and like all forms of precipitation, it has no salt. 5. a) 12.3% of 2.5% = 0.31% b) 90% of 0.4% of 2.5% = 0.009% c) 9% of 0.4% of 2.5% = %

Cloud Classification 1.Cumulus (‘heap’) Fig 6a p532 Billowing, rounded shape that tend to grow vertically Indicate unstable weather Usually form as a result of convection currents, orographic lifting or when a cold air front pushes into a warm air mass

Cumulus

2. Stratus (‘stretched out’) fig 6 b p532 Flattened, layered shape that tend to grow horizontally Indicate stable weather Form where a front of a warm air mass overruns a cold air mass

Stratus

3.nimbus or the prefix nimbo- is used to name the darker, rain- holding type of cloud

Further Classification At low altitudes the clouds (below 2000 m) are named using the terms for shape without addition of any prefix. (stratus or cumulus) To distinguish clouds located at higher altitudes a prefix is added to the basic shape name. The prefix, alto- is used for clouds located in the mid altitudes ( m).

Further Classification The prefix, cirro- is used for clouds at higher altitudes ( m). The term cirrus is given to the highest clouds ( m). FIGURE 7, p. 533 **STUDY**

QUESTIONS P. 534 – #1, 3, 4, 5, 6

1. Water at ground level absorbs energy, causing some of it to evaporate; this adds water vapor to the air. Air near the ground absorbs energy from its surroundings and rises when it becomes less dense than the surrounding air. The rising air carries water vapor with it to higher altitudes. There the air expands due to lower pressure and absorbs energy released by the water vapor that is cooling and condenses into a cloud

3. A) 3000m B) 6000m C) below 2000m D) from low to 7000m

4. A) Altocumulus clouds are puffy grey or white, found around 3000m; they are interspearsed with patches of clear sky. B) cirrostratus clouds are thin and veil-like and are at about 6000m. They can produce halos around the sun or moon

C) Nimbostratus are dark rain clouds below 2000m D) Stratus clouds are uniform sheet clouds at about 2000m; they often bring drizzle

5. A) A contrail (a contraction of condensation trail) resembles a cirrus cloud B)The exhaust contains water vapors, and at such a high altitude the vapor added to the cold air turns into ice crystals, creating the contrail

6. A) You would expect to find orographic clouds around large mountains such as the mountain chains on the west coast of North America B) Convective clouds would be found where a lot of warm air rises, carrying moisture with it. Most areas around the equator where it is very hot. C) Most areas of Canada and the USA