CLOUD FORMATION There are 3 things required for clouds to form: Water vapour Change in temperature or pressure Condensation nuclei (dust, smoke, etc)

CLOUD CLASSIFICATION Low-level = less than 2km Mid-level = between 2 and 7km High level = greater than 7km Alto = mid-level Cirrus = wispy, high-level clouds Stratus = featureless blanket Nimbus = rain cloud Cumulus = fluffy rolling clouds

STRATUS CLOUDS Low-level clouds, closest to Earth No definite form Often cover whole sky Usually associated with moist weather

Cumulus Clouds Higher altitudes than stratus White fluffy masses Often associated with fair weather May cause heavy rainfall

Stratocumulus Clouds Low-level clouds globular masses or dark and light rolls Common during winter Form in the wake of cold front

Nimbostratus Clouds Low-level Shapeless, irregular edges Thick, block sun Bring steady precipitation

Altocumulus Clouds Mid-level clouds Cover sky Globular masses and rolls Associated with rain or thunderstorms

Altostratus Sheets of blue and gray that cover most of the sky Sometimes thick enough to block the sun, leaving a light area in the sky Appear a few hours ahead of a warm front, and indicate a decrease in pressure.

Cumulonimbus Clouds Range in altitude Tall. Top in cold upper air with warm base. (anvil shaped) Called “thunderheads” From the warm base lightning, thunder and precipitation originate

CIRRUS CLOUDS High altitude clouds Ice crystals Thin, wispy, feathery Distant storm or change in weather

Cirrocumulus Clouds Very high altitudes Formed by ice crystals “mackerel sky”- small, globular, white masses or ripples Approaching warm front or storm

Cirrostratus clouds a layer of cirrus clouds that spreads across the sky make the sky pale or white in appearance indicate approaching precipitation

CLOUD QUIZ SHOW

For each of the following pictures: identify the type of cloud and indicate the characteristics that allowed you to make this identification

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Altocumulus midlevel. globular. 1. Altocumulus midlevel. globular.

whole sky. no defined form. 2. Stratus whole sky. no defined form.

3. Cumulus fluffy

4. Cirrus high level. wispy.

Cirrocumulus “mackerel sky” 5. Cirrocumulus “mackerel sky”

whole sky. no definite shape. 6. Stratus whole sky. no definite shape.

Cumulonimbus anvil shape 7. Cumulonimbus anvil shape

Nimbostratus dark rain cloud. sky cover. 8. Nimbostratus dark rain cloud. sky cover.

fluffy. lots of sky cover. 9. Stratocumulus fluffy. lots of sky cover.

10. Cumulus fluffy