Weather Temporary behavior of atmosphere (what’s going on at any certain time) Small geographic area Can change rapidly

Weather --The study of weather is meteorology --Someone who studies weather is called a meteorologist

What Factors Affect Weather?  The Sun  The Water Cycle  The Atmosphere  The Ocean

How Does the Sun Affect Weather? It warms the atmosphere & oceans It keeps the water cycle going

The Water Cycle All the water on the planet is recycled in this manner!

Parts of the Cycle Evaporation Evaporation—Water going from a liquid to a gas (gains energy from the sun)

Parts of the Cycle *Transpiration—evaporation of water from/out of plants. Locate this on the diagram! transpiration

Parts of the Cycle Condensation Condensation—Water going from a gas to a liquid (cools or loses energy) When this happens in the atmosphere, CLOUDS form.

Parts of the Cycle Precipitation—when water falls out the atmosphere. Forms when the water droplets in clouds become too heavy to stay up.

Precipitation Liquid water = rain Frozen water = snow or sleet or hail

Water Cycle Advanced by Brainpop

How does the atmosphere affect weather? The atmosphere is a mixture of gases that surrounds the Earth Has five different layers; each has different properties Weather occurs in the layer closest to Earth (troposphere)

Air Masses = body of air with a certain temperature and moisture level Can be warm or cold Can contain a lot of moisture or not a lot of moisture

Fronts = places where air masses meet 4 Types: Warm, Cold, Occluded, Stationary Each kind can bring different kinds of weather

Occluded Front:Stationary Front:

How does Air Pressure affect weather? How much the earth’s atmosphere is pressing down on us Measured with a BAROMETER If it CHANGES, then new weather is on the way: Falling Air Pressure = stormy weather coming Rising Air Pressure = fair weather coming Steady Air Pressure = no change is coming

Winds Winds = created from differences in air pressure Moves from areas of HIGH to LOW pressure Greater the difference in pressure, the FASTER the wind blows Measured with wind vanes and anemometers

Global Winds Thousands of kilometers long; can cause weather to move in different directions Jet stream, prevailing westerlies, doldrums, horse latitudes, trade winds

Global Winds Caused by the temperature difference in different regions Hot Tropical Regions—causes air to rise Cold polar Regions—causes air to sink

Global Winds Also affected by Earth’s Spin Coriolis Effect = causes winds to curve to the right in the N. Hemisphere; to the left in the S. Hemisphere

Relative Humidity moisture Measure of the amount of moisture in the air compared to what the air could hold How “full” of water the air is Expressed as % saturated 100% relative humidity = saturated air

Relative Humidity Controlled by temperature Warm 1. Warm air holds more moisture than cool air (more space for water vapor between air molecules) warms decreases 2. As air warms, relative humidity decreases cools increases 3. As air cools, relative humidity increases

Dew Point =Temperature at which the air is saturated (100% relative humidity) Several events can occur when the dew point temp. is reached: 1. If dew point temp. is above freezing: liquid a. water vapor condenses as liquid b. dew will form on surfaces

Dew Point c. cloud droplets will form in air 2. If dew point temp. is below freezing: a. water vapor condenses as a solid b. frost on surfaces c. snow (or hail) in the air

How does the Ocean affect weather? Ocean currents affect the temperature of the land they pass by Cold ocean currents = cooling effect Warm ocean currents = warming effect Temperature changes affect pressure – which then creates WINDS Winds blow this cooling or warming effect over the land