Weather &

Climate

1. Air is empty space.

2. Earth’s atmosphere is important to living organisms.

3. Uneven heating in different parts of the atmosphere causes global wind patterns

4. Warm air sinks and cold air rises

5. Uneven heating in different parts of the atmosphere causes global wind patterns

6. Warm air sinks and cold air rises

Do you agree or disagree?

• pressure

• density

• mass

• atmosphere

• altitude

• radiation

• conduction

• convection

• wind

• Coriolis effect

Vocabulary

• Air is all around us, and although we cannot see it, it has mass.

• Recall that mass is the amount of matter in an object, and that matter is anything that has mass and takes up space.

• Because air has mass, it also has pressure

• Air pressure is the pressure caused by the weight of a column of air pushing down on an area

Air

• The atmosphere is the outermost Earth System of gases and particles of matter

• The atmosphere is essential to life on Earth:– contains oxygen and carbon dioxide, and water

necessary for life– acts like insulation on a house to keep the Earth

warm– protects living organisms from some of the Sun’s

harmful rays– protects Earth’s surface from being hit by meteoroids

What is the atmosphere?

The atmosphere

Why is the atmosphere important?

Layers of the Atmosphere

• The atmosphere has several different layers

• Each layer has unique properties, including composition of gases and how temperature changes with altitude

• Altitude is height above sea level

The atmosphere

Layers of the Atmosphere

The Troposphere

• The atmospheric layer closest to Earth’s surface

• Extends from the face of Earth’s surface to altitudes between 8 – 15km

• Temperature decreases as you move away from the surface

• This is the layer where most of Earth’s weather occurs

The atmosphere

The Stratosphere

• The atmospheric layer directly above the troposphere

• Extends from about 15 km to about 50 km

• Contains the ozone layer• The area of the stratosphere with a high

concentration of ozone

• Due to the ozone layer, temperature increases as altitude increases within the stratosphere

The atmosphere

The Mesosphere and Thermosphere• The mesosphere extends from the stratosphere (50 km)

to about 85km• The thermosphere can extend from the mesosphere to

more than 500 km above Earth’s surface• Combined these layers are much broader than the

troposphere and stratosphere, yet only 1% of the atmosphere’s gas molecules are found here

• The ionosphere is a region within the mesosphere and thermosphere that contains ions

• Between 60 km and 500 km• The ions in this layer reflect AM radio waves transmitted

at ground level• Auroras- stunning display of lights in the ionosphere

– Ions from the Sun strike air molecules, causing them to emit vivid colors of light (can be viewed at higher latitudes)

The atmosphere

The Exosphere

• The atmospheric layer furthest from Earth’s surface

• Extends from 500 km out to space– It has no definite end, the molecules here can escape

Earth’s gravity and travel into space

• Pressure and density is so low here that individual gas molecules rarely strike each other

• Molecules here move at incredibly fast speeds after absorbing the Sun’s radiation

The atmosphere

Energy in the Atmosphere

• Energy in the form of heat is transferred throughout the atmosphere

• Recall that there are three types of heat transfer– Radiation – transfer of heat through space– Conduction – transfer of heat through direct

contact– Convection – transfer of heat within a fluid/air

• The troposphere is heated mostly through convection

The atmosphere

• The horizontal movement of air from an area of high pressure to an area of low pressure

• Winds are caused by differences in air pressure

• Winds are described by their direction and speed– The name of a wind tells you where it is coming

from, a south wind blows from the south towards the north

• Wind direction is determined with a wind vane

• Wind speed is measured with an anemometer

Wind

Weather Patterns

Local Winds

Weather

• Winds that blow over short distances

• Local winds are caused by the unequal heating of Earth’s surface within a small area

Weather Patterns

• Winds that blow steadily from specific directions over long distances

• Like local winds they are created by unequal heating of Earth’s surface, but unlike local winds they occur over a large area

• Recall that areas near the equator receive the most direct sunlight, and are therefore warmer than the poles. This difference in temperature creates giant convection currents

• Warm air rises at the equator and cold air sinks at the poles, therefore air pressure tends to be lower near the equator and greater near the poles

Global Winds

• The change that Earth’s rotation causes in the motion of objects and that explain how winds curve

• Global winds in the Northern Hemisphere gradually turn towards the right and in the Southern Hemisphere winds curve to the left

The Coriolis Effect

Weather Patterns

Global Wind Belts• Doldrums: areas near the equator with little or no winds; calm

areas where warm air rises

• Horse Latitudes: areas at 30 degrees north and south of the equator; calm areas of falling air.

• Trade Winds: blow from the horse latitudes toward the equator; generally blow from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.

• Prevailing Westerlies: blow west to east and away from the horse latitudes; play an important role in the weather of the United States.

• Polar Easterlies: cold air near the poles sinks and flows back toward the lower latitudes; blow east to west; major effect on the weather in the U.S.

• Jet Streams: bands of high-speed winds about 10 kilometers above Earth's surface.

Weather Patterns

Global Wind Belts

Air Masses• Scientists classify air masses according to two

characteristics: temperature and humidity

• Temperature affects air pressure

• Cold, dense air has a higher pressure, while warm, less dense air has a lower pressure

• Tropical: warm, form in tropics, low air pressure• Polar: cold, form at the poles, high air pressure• Maritime: humid, form over oceans• Continental: dry, form over land

Weather Patterns

Types of Air Masses

Air Masses• Air masses are referred to as either maritime or

continental, and as either tropical or polar

– Maritime Tropical: humid, warm air mass– Maritime Polar: humid, cold air mass– Continental Tropical: dry, warm air mass– Continental Polar: dry, cold air mass

Weather Patterns

1. Air is empty space.

2. Earth’s atmosphere is important to living organisms.

3. Uneven heating in different parts of the atmosphere causes global wind patterns

4. Warm air sinks and cold air rises

5. Uneven heating in different parts of the atmosphere causes global wind patterns

6. Warm air sinks and cold air rises

What do you think now?

Agree or Disagree?