WATER IN THE

ATMOSPHERE

WHAT DO FOGGED-UP WINDOW ON A COLD WINTER MORNING AND A BAD HAIR

DAY IN COMMON?

HUMIDITY• The amount of water vapor in the air.• Warm, tropical air tends to contain more

water vapor than cold, polar air does.

RELATIVE HUMIDITY-is the ratio of the amount of water vapor in the air to the maximum amount of water vapor that can exist at that temperature.-when relative humidity reaches 100%, AIR IS SAID TO BE SATURATED.

RELATIVE HUMIDITYThe maximum amount of water that can

exist as a gas is greater at high temperature than at low temperature.

Ex: After sunset, the temperature often decreases, and so the maximum amount of water vapor that the atmosphere can hold also decreases.

Dew point• The temperature at which air becomes

saturated.• If the temperature drops further, water

vapor will condense.

WATER VAPOR TYPICALLY CONDENSES AS:

1. DEW 3. CLOUDS OR FOG2. FROST

1. DEW- Is water vapor that

condenses on Earth’s surface.

2. FROST- Forms when the dew

point of air is below freezing.

- Is formed when water vapor in air changes directly from a gas to solid crystals.

CLOUDS

CLOUDS FORMATIONCLOUD – is a dense, visible mass of tiny water droplets or ice crystals that are suspended in the atmosphere.

CLOUDS FORM as warm, moist air rises and water vapor condenses in the atmosphere

CLOUDS FORMATION

CLASSIFYING CLOUDS

• THREE BASIC CLOUD FORMS:

1. Stratus

2. Cumulus

3. Cirrus

CLASSIFYING CLOUDS1. STRATUS CLOUDS- Comes from Latin

word meaning “to spread out”

Nimbo- or Nimbus- -is added to a cloud’s name, it means that the cloud produces precipitation.

Ex. Nimbostratus clouds

Alto--is added to a cloud’s name, it means middle-level clouds.

• Altostratus clouds

CLASSIFYING CLOUDS2. CUMULUS CLOUDS-come from Latin for “heap”-fair-weather clouds

3. CIRRUS CLOUD- Thin, white, wispy

clouds, often with a feathery or veil-like appearance.

Cirros--is used to described high-altitude clouds

CLASSIFYING CLOUDS

FOG-is a cloud that is near or touching the ground.

-it often form when warm, moist air passes over land.

FORMS OF PRECIPITATIONPRECIPITATION – occurs when water droplets or ice crystals in clouds join together and become large enough to fall to the ground without evaporating.

THE MOST COMMON TYPES OF PRECIPITATION:

RAIN SNOW

SLEET HAIL

FREEZING RAIN

WEATHER PATTERN

S

Air MassesIt is a large body of air that has fairly uniform physical properties.

Characteristics of Air Mass

1. Air mass must be large in size2. Air mass must have a uniform

and consistent makeup at all points within the air mass.

3. Air mass must be physically bound together, traveling across the atmosphere as a single unit.

HOW DO AIR MASSES FORM?

It forms when a large body of air becomes fairly stationary over a region of Earth’s surface or as air moves over a large, uniform region.

CLASSIFICATIONS OF AIR MASSES

Maritime Polar

ArcticContinental Polar

Continental TropicalMaritime Tropical

CLASSIFICATION OF AIR MASSES

1. MARITIME AIR MASS - forms over water

2. CONTINENTAL AIR MASS – forms over land

3. POLAR AIR MASS – forms North of 50º or

South of 50º, where it is often extremely cold.

4. TROPICAL AIR MASS – originates in the

tropics, where it is warm.

AIR MASSES THAT MOST AFFECT WEATHER

• MARITIME POLAR –cold and moist, and often bring heavy precipitation to coastal areas.

• CONTINENTAL POLAR – bring cold and dry air .

• MARITIME TROPICAL – bring warm, moist air and are often accompanied by fog or rain.

• CONTINENTAL TROPICAL – bring hot, dry air.

FRONTSThe sharply

defined boundary that forms when

two unlike air masses meet.

TYPES OF FRONTS

Stationary front• When two

unlike air masses have formed a boundary but neither is moving front.

• Often result in clouds and steady rain or snow for several days.

COLD FRONTOccurs when a cold

air mass overtakes a warm air mass.

cumulus and cumulonimbus clouds

Strong winds, severe thunderstorms and hail.

Warm FrontOccurs when a

warm air mass overtakes a cold air mass.

Steady rain, heavy showers or thunderstorms.

OCCLUDED FRONTwhen a warm

air mass is caught between two cooler air masses.