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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