CloudsClouds

Science 1206Science 1206

You will learnYou will learn

• identify and define the three main identify and define the three main categories of clouds: convective, categories of clouds: convective, frontal, and orographic frontal, and orographic

• classify clouds into their separate classify clouds into their separate types types

• describe the conditions necessary to describe the conditions necessary to form fog form fog

Cloud Formation:Cloud Formation:

• A consequence of the evaporation of A consequence of the evaporation of water followed by condensation of water followed by condensation of water droplets during the water cycle water droplets during the water cycle is the formation of clouds. There are is the formation of clouds. There are three ways in which clouds are formed three ways in which clouds are formed - -

• convective, convective, • frontal, frontal, • and orographic. and orographic.

Convective cloudsConvective clouds

• Are the result of evaporation of water Are the result of evaporation of water which rises into the atmosphere as which rises into the atmosphere as air near the Earth's surface is heated.air near the Earth's surface is heated.

• As the air rises, it expands and As the air rises, it expands and cools. cools.

• These condensed particles of water These condensed particles of water form convective clouds. form convective clouds.

Frontal cloudsFrontal clouds

• Form when a warm air mass meets a cooler Form when a warm air mass meets a cooler air mass. air mass.

• Since warm air masses are generally less Since warm air masses are generally less dense than cooler air masses, the warm air dense than cooler air masses, the warm air mass tends to move above the cooler air mass tends to move above the cooler air mass. mass.

• As the warm air mass rises above the cooler As the warm air mass rises above the cooler air mass, frontal clouds form due to the air mass, frontal clouds form due to the expansion and resulting cooling of the air. expansion and resulting cooling of the air.

Orographic cloudsOrographic clouds

• They form as They form as warm air warm air masses masses move up the move up the sides of a sides of a mountain. mountain.

FogFog

• Is actually a cloudIs actually a cloud formed at or near formed at or near ground level.ground level.

• Fog may be formed as warm air Fog may be formed as warm air moves over cold land masses, over moves over cold land masses, over snow fields, or cold bodies of water.snow fields, or cold bodies of water.

• Fog may also form as a result of Fog may also form as a result of orographic lifting. orographic lifting.

Cloud Classification:Cloud Classification:

• There are three terms most often There are three terms most often used to describe the form of the used to describe the form of the cloud - stratus and cumulus. cloud - stratus and cumulus.

• The third term The third term nimbusnimbus or the prefix or the prefix nimbo-nimbo- is used to name the darker, is used to name the darker, rain-holding type of cloud. rain-holding type of cloud.

Stratus cloudsStratus clouds

• Stratus cloudsStratus clouds are are generally flat and generally flat and long. long.

• Stratus clouds Stratus clouds indicate stable indicate stable weather conditions weather conditions and also result in and also result in overcast conditions. overcast conditions.

Cumulus cloudsCumulus clouds

• Cumulus cloudsCumulus clouds are somewhat flat are somewhat flat on bottom but have on bottom but have a bilious upper a bilious upper surface. surface.

Names and Altitude of Names and Altitude of CloudsClouds

• The prefix, The prefix, alto-alto- is used for clouds is used for clouds located in the mid altitudes (3000-located in the mid altitudes (3000-7000 m). The prefix, 7000 m). The prefix, cirro-cirro- is used is used for clouds at higher altitudes (6000-for clouds at higher altitudes (6000-8000 m). The term 8000 m). The term cirruscirrus is given to is given to the highest clouds (7000-8000 m). the highest clouds (7000-8000 m).

To DoTo Do

• Read 13.11 "Clouds and Fog" on Read 13.11 "Clouds and Fog" on pages 530-534. Answer questions 1-6 pages 530-534. Answer questions 1-6 from "Understanding Concepts" on from "Understanding Concepts" on page 534. page 534.

1. When are convective clouds 1. When are convective clouds formed?formed?

a.a. in a high pressure system with cool, dry, in a high pressure system with cool, dry, falling air falling air

b.b. moist air near the ground absorbs energy moist air near the ground absorbs energy from a heated surface such as a lake, asphalt, from a heated surface such as a lake, asphalt, or dirtor dirt

c.c. when a mass of moist air rises up the side of a when a mass of moist air rises up the side of a mountainmountain

d.d. the leading edge of a large moving mass of air the leading edge of a large moving mass of air meets another mass at a different meets another mass at a different temperaturetemperatureAnswer B

When are frontal clouds When are frontal clouds formed? formed? • a. in a high pressure system with cool, dry, falling a. in a high pressure system with cool, dry, falling

air air

• b. moist air near the ground absorbs energy from b. moist air near the ground absorbs energy from a heated surface such as a lake, asphalt, or dirta heated surface such as a lake, asphalt, or dirt

• c. when a mass of moist air rises up the side of a c. when a mass of moist air rises up the side of a mountainmountain

• d. the leading edge of a large moving mass of air d. the leading edge of a large moving mass of air meets another mass at a different temperaturemeets another mass at a different temperature

Answer D

3. When are orographic clouds 3. When are orographic clouds formed? formed? • a. in a high pressure system with cool, dry, falling a. in a high pressure system with cool, dry, falling

airair

• b. moist air near the ground absorbs energy from b. moist air near the ground absorbs energy from a heated surface such as a lake, asphalt, or dirta heated surface such as a lake, asphalt, or dirt

• c. when a mass of moist air rises up the side of a c. when a mass of moist air rises up the side of a mountainmountain

• d. the leading edge of a large moving mass of air d. the leading edge of a large moving mass of air meets another mass at a different temperature meets another mass at a different temperature

Answer C

4. Which type of clouds reach 4. Which type of clouds reach the highest altitude? the highest altitude?

• a. cirrusa. cirrus

• b. cumulusb. cumulus

• c. stratusc. stratus

• d. nimbocumulus d. nimbocumulus

ANSWER A

5. Which type of clouds are 5. Which type of clouds are billowing, fluffy, and rounded billowing, fluffy, and rounded in shape? in shape? • a. cirrusa. cirrus

• b. cumulusb. cumulus

• c. stratusc. stratus

• d. nimbocumulus d. nimbocumulus

ANSWER B

6. Which cloud type is 6. Which cloud type is associated with stable weather associated with stable weather conditions? conditions? • a. cirrusa. cirrus

• b. cumulusb. cumulus

• c. stratusc. stratus

• d. nimbocumulus d. nimbocumulus

ANSWER C

7. Which type of cloud is 7. Which type of cloud is formed very close to land? formed very close to land?

• a. cirrusa. cirrus

• b. cumulusb. cumulus

• c. stratusc. stratus

• d. fog d. fog ANSWER D

OceansOceans

• Nearly 70% of the Earth is covered Nearly 70% of the Earth is covered by oceans, and because the by oceans, and because the equatorial region of the Earth is equatorial region of the Earth is mostly ocean (most land is located in mostly ocean (most land is located in the Northern Hemisphere) the Northern Hemisphere)

OceansOceans

• The major oceans of the Earth The major oceans of the Earth include the include the Arctic OceanArctic Ocean around the around the North Pole, the North Pole, the Antarctic OceanAntarctic Ocean around the South Pole, the around the South Pole, the Pacific Pacific OceanOcean (which is the largest of all the (which is the largest of all the oceans), the oceans), the Atlantic OceanAtlantic Ocean, and , and the the Indian OceanIndian Ocean. .