Weather Elements

Summary from Lesson 2____________ is the passage of energy, particularly

heat and electricity, through an object. An example is a frying pan

____________ is the process whereby air absorbs heat energy. Warm air is forced upward as cold air flows displace the warm air.

The horizontal transfer of a heat, caused by air movement is called ________________. A good example is fog.

________________ is the rate at which the Earth’s surface is heated by solar radiation.

Conduction

Convection

Insolation

Advection

Weather ElementsKnow basic facts and general principles of the elements of weather.1. Identify types of clouds.2. Identify types of air masses and fronts.

Overview1. Clouds2. Air Masses and Fronts

Low Clouds (300 – 6,500 ft)

Stratus• Sheet - like cloud.• No turbulence.• May be risen fog.• Light drizzle or snow.• Close to Earth’s

surface.• Can hide danger.

Low CloudsStratocumulus

• Rolls or global masses.

• Bulbous protrusions.• Heavy rain and snow• Varying turbulence.• Masks higher severe

cloud buildups.

Low Clouds

Cumulonimbus• Vertical growth

group.• Top has anvil shape.• High winds, snow,

hail, rain, lightning, and tornadoes.

• Extreme turbulence.

Middle Clouds(6,500 – 20,000 ft)

Altostratus• Relatively thin.• Sun may be seen

through veil.• Ice crystals and

super-cooled water.• Light precipitation.• Poor surface

visibility.

Middle CloudsAltocumulus

• Wavy solid clouds with rounded outline.

• Light intermittent rain or snow.

• Commonly followed by thunderstorms.

• Poor visibility and moderate surface winds.

High Clouds(20,000 ft and up)Cirrus

• Thin feathery clouds.• No precipitation.• Sign of approaching

bad weather.

High CloudsCirrocumulus

• Thin clouds.• Indicates high-level

instability.• Similar to cirrostratus

but they have a slightly “bumpy” appearance.

Fog TypesRadiation Fog

• Formed at night when land surfaces radiate much of the heat absorbed from the Sun back into space.

• The cool land surface cools the air near it to below the dew point and fog is formed.

Fog TypesAdvection Fog

• Formed when wind blows moist air over a cold surface.

• When the surface cools the air to its dew point temperature, fog is formed.

Fog TypesUpslope Fog

• Results when wind carries moist air up to a mountain slope or sloping land.

• The air cools to its dew point as it rises and water vapor then condenses into fog.

Air MassA large body of air (usually extending over

an area 1,000 or more miles across) which has generally the same temperature and moisture content within the entire mass.

Characteristics of Air MassesCold air masses move more rapidly than

warm air masses.

FrontsThe boundaries between air masses are

called frontal zones or fronts.• If a cold air mass replaces a warmer air mass,

the boundary is called a cold front.• If a warm air mass replaces a cold air mass,

the boundary is called a warm front.

FrontsCold Fronts

• As warm air is forced upward, it cools, condenses into clouds, creating thunderstorms.

• Squall lines develop ahead of the front.

FrontsWarm Fronts

• Front slips upward over cool air and forms a wedge.

• Rises slowly which delays condensation.

• As front approaches other clouds, skies darken.

• Near the frontal boundary, clouds are low, gentle rain falls and visibility is poor.

Summary1. Clouds2. Air Masses and Fronts