Weather Chapter 1: Section 1 The Atmosphere Weather is the condition of Earth’s atmosphere at a particular place and time. Atmosphere: layer of gases that surrounds the planet. 78% nitrogen 21% oxygen 1% other gases(CO 2, argon)

Air pressure: the force of a column of air pushing down on an area. *measured with a barometer *decreases as altitude increases Low pressure = rainy, cloudy High pressure = clear skies

Air has mass, density, and pressure. Warm air = less dense Cool air = more dense

Measuring Air Pressure –Mercury barometer (inches of mercury) –Aneroid barometer (millibars) Barometers

mb = ________ inches mb = ________ inches inches = ________ mb inches = ________ mb

Air Pressure

Layers of the Atmosphere Section 4 Four layers based on changes in temperature.

Troposphere: lowest layer where weather occurs. WHY?*The only layer containing water*

Stratosphere: has the ozone (O 3 ) layer. Mesosphere: coldest layer.

Thermosphere: outer layer and is very hot.

Earth’s Atmosphere

Weather Factors Chapter 2 1.Energy: travels from the Sun to Earth by electromagnetic waves in the form of light, infrared radiation(heat), and ultraviolet radiation. Energy is absorbed, reflected, and scattered by the atmosphere.

A Green house

Greenhouse Effect: is when heat is trapped by the gases in the atmosphere. CO 2 – burning fossil fuels increases amount.

2. Heat: moves throughout the atmosphere by conduction, convection, and radiation affecting weather. 3. Wind: is a horizontal movement of air from high pressure to low pressure. Named by where they come from. Anemometer: measures wind speed.

Wind-chill factor: increased cooling caused by wind.

Local Winds: caused by unequal heating of Earth’s surface within a small area. Examples: Sea breeze Land Breeze

Global Winds: caused by movement of air between the equator and poles.

4.Water: Water Cycle: is the movement of water between the atmosphere and Earth’s surface. *causes= humidity, clouds, and precipitation.

Humidity: amount of water vapor in the air. Relative Humidity: % of vapor in the air compared to the maximum amount the air can hold at that temperature. *Measured with a psychrometer

Clouds: form when water condenses in the atmosphere when it cools. Examples: CumulonimbusCirrus

StratusCumulus

Precipitation: any form of water that falls from the sky. Examples: Rain, sleet, snow, hail

*measured with a rain gauge *Acid rain: man made form of pollution *Natural pollutant: Pollen, volcanic ash

Mountain Weather

Weather w.s. # 6

Weather Patterns Chapter 3 Air Masses and Fronts: Air masses are classified based on their temperature and humidity. Temperature: hot/cold Humidity: moist/dry

Tropical – warm = (T) Polar – cold = (P)

Maritime – moist =(m)Continental – dry =(c) Ex: mP air is ______ & ________ moistcold

Fronts: Areas where air masses meet and do NOT mix. 1. Cold - violent weather at the front.

2. Warm - rain ahead of front. 3. Stationary – neither air mass is strong enough to move the other.

For all fronts, the direction of symbols tells you direction front is moving 4. Occluded – warm air trapped above and between two cold air masses. southeast northeast

Quiz Time… What type of front is at A? A cold

Storms Storms: are a violent disturbance in Earth’s atmosphere. Thunderstorms: from cumulonimbus clouds.

Tornadoes: are fast moving funnel shaped clouds.

Hurricanes: are large tropical storms forming over warm water

Isobars: show areas of equal air pressure.

What is the barometric pressure at Z? Z 1012mb

Lake Effect Snow