WeatherChapter 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% nitrogen21% oxygen1% other gases(CO2, 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, cloudyHigh pressure = clear skies

Air has mass, density, and pressure.

Warm air = less denseCool air = more dense

Measuring Air Pressure

– Mercury barometer• (inches of mercury)

– Aneroid barometer• (millibars)

Barometers

1013.2 mb = ________ inches

1022.8 mb = ________ inches

30.53 inches = ________ mb

29.81 inches = ________ mb

29.92

30.20

1034.0

1009.5

Air Pressure

Layers of the AtmosphereSection 4

Four layers based on changes in temperature.

Troposphere: lowest layer where weather occurs.

WHY?*The only layer containing water*

Stratosphere: has the ozone (O3) layer.

Mesosphere: coldest layer.

Thermosphere: outer layer and is very hot.

Earth’s Atmosphere

Weather FactorsChapter 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.

CO2 – 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:

Cumulonimbus Cirrus

Stratus Cumulus

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 PatternsChapter 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 ______ & ________moist

cold

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

StormsStorms: 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?

Z1012mb

Lake Effect Snow