Earth’s Weather PatternsChapter

10

Prior Knowledge

• What is weather?

• What makes up the Atmosphere?

• How can you track severe storms?

What Makes up the Atmosphere?

1. Atmosphere- layers of air that surround Earth.

A.Nitrogen and Oxygen make up most of Earth’s atmosphere.

B.B. Water vapor- water in the form of Water vapor- water in the form of a gasa gas.

C.Ozone- O3 Oxygen gas that absorbs ultraviolet radiation from the sun.

5 layers of Atmosphere

* The layers are divided by major temperature changes.

• Troposphere- *closest to earth- This is

where we live!*where most weather occurs. *Convection currents- air

movements (cool air sinks, warm air rises)

• 2. Stratosphere- atmosphere layer that extends from Troposphere to 50 km.

• thin dry air • ozone layer absorbs UV rays from the sun• Jet airplanes fly in this area because the air

is stable• Jet Stream- strong, eastward wind that

blows horizontally around the Earth.

• 3. Mesosphere- atmosphere layer that extends from about 50 km to about 80 km above the earth’s surface.

• Upper region is the coldest region of the atmosphere

• This layer helps protect Earth from meteoroids – they burn up most meteoroids by the friction caused as they pass through.

4. Thermosphere- - atmosphere layer that begins at about 80 km and has no defined upper limit. “Heat sphere” or “Warm layer”

*Extremely high temperatures.* Auroras*Where space shuttles orbit

Ionosphere-Lower thermosphere.– Ions- electrically charged particles. – AM radio waves bounce off ionosphere back to Earth.

Exosphere- Upper thermosphere- very thin layer

5. Exosphere- *outermost layer* endless boundary to space.

10-2 What is Weather?

• Weather- the condition of the atmosphere at a particular time and place.

• Air pressure- the weight of air pressing down on a unit of area.

• Relative humidity- a ratio of actual amount of water vapor I air to the total amount of water vapor the air could contain at that temperature.

• Front- boundary between two air masses that collide.

•Warm front- Warm air to cooler air

•Cold front- Cold air to warmer air

•Stationary front- boundary between 2 air masses that are not moving against each other.

– (Can form clouds when warm air mixes with cold air. Can also lead to light rain or snow that lasts a long time because the front is not moving.)

•What causes thunderstorms?–When cold air masses move very rapidly and push up a lot of warm air very quickly. This forms clouds with a lot of moisture.

Types of Clouds

• Cirrus• Cirrocumulus• Cirrostratus• Altostratus• Altocumulus• Stratus• Cumulus• Cumulonimbus

•Wind- movement of air from an area of higher pressure to area of lower pressure.

• Climate- the average of all weather conditions in an area over a period of time. (precipitation, temperature, and ocean currents influence climate)

10-3How Can You Track Severe

Storms?

• Forecast- a prediction about the weather (accurate up to 3 to 5 days into the future)

• Meteorologist- scientist who study weather conditions to provide forecasts.

• Instruments used by meteorologists– Thermometer measures

temperature.– Barometer measures air pressure.– Anemometer to measure wind

speed.– Weather balloons and satellites collect

data on weather patterns and storms in the troposphere. They record air pressure, temperature and humidity.

- Thunderstorms- a strong storm with rain, lightning and thunder.

- Form from warm humid air moving upward quickly through colder surrounding air. As warm air cools, water vapor condenses into droplets. Raid and winds blow up and down with in the cloud. Negative charges build up in the bottom of the cloud and travel through the air to ground as lightning. Intense heat makes sound waves, which cause the sound of thunder.

• Tornado- a violent rotating column of air that extends downward from thunder cloud and touches the ground.

• Hurricane - a large, rotating tropical storm system with wind speeds of at least 74 miles/hour. – 3 ways they cause damage

• 1. violent winds• 2. flooding rains• 3. storm surges

• Blizzards- a winter storm with strong winds and large amounts of heavy, blowing snow.

•Develop because of differences in air pressure.

•Frostbite- an injury to the skin from freezing.

•Hypothermia- condition in which the body temperature falls dangerously low.