UNIT THREE: Matter, Energy, and Earth

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UNIT THREE Matter, Energy, and Earth

• Chapter 8 Matter and Temperature
• Chapter 9 Heat
• Chapter 10 Properties of Matter
• Chapter 11 Earths Atmosphere and Weather

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Chapter Eleven Earths Atmosphereand Weather

• 11.1 Earths Atmosphere
• 11.2 Weather Variables
• 11.3 Weather Patterns

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11.3 Learning Goals

• Define front.
• Contrast warm and cold fronts.
• Discuss the weather conditions associated with
  high-pressure and low-pressure systems.
• Describe the characteristics of clouds and
  predict the weather based on the appearance of
  clouds.

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11.3 Air masses and fronts

• An air mass is a large body of air with
  consistent temperature and moisture
  characteristics throughout.
• Two air masses that affect the United States are
  the continental polar air mass and the maritime
  tropical air mass.

Changing conditions and global winds cause these
air masses to move.
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11.3 Fronts

• A cold front occurs when cold air moves in and
  replaces warm air.

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11.3 Fronts

• A warm front occurs when warm air moves in and
  replaces cold air.

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11.3 Fronts

• On a weather map, a cold front is shown using a
  line marked with triangles.
• The triangles point in the direction the front is
  moving.
• A warm front is shown using a line marked with
  semicircles.

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11.3 Low- and high-pressure areas

• When a cold front moves into a region and warm
  air is forced upward, an area of low pressure is
  created near Earths surface at the boundary
  between the two air masses.

• A center of high pressure tends to be found where
  a stable cold air mass has settled in a region.

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11.3 Clouds

• A cloud is a group of water droplets or ice
  crystals that you can see in the atmosphere.

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11.3 Types of clouds

• Different conditions cause different clouds.
• Cumuliform clouds include
• cirrocumulus
• altocumulus
• cumulus
• cumulonimbus

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11.3 Cloud formation

• Stratiform clouds form when a large mass of
  stable air gradually rises, expands, and cools.
• Stratiform clouds include
• cirrostratus
• altostratus
• stratus
• nimbostratus

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11.3 Cloud formation

• Sometimes a cloud formation combines aspects of
  both cumuliform and stratiform clouds.
• We call these clouds stratocumulus clouds.

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11.3 Cloud formation

• Cirrus clouds are thin lines of ice crystals high
  in the sky, above 6,000 meters.
• They are just a thin streak of white across a
  blue sky.

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11.3 Thunderstorms

• Thunderstorms occur because of convection in the
  atmosphere.
• The downdraft and updraft form a type of
  convection cell called a storm cell within the
  cloud.

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11.3 Lightning

• Lightning is a bright spark of light that occurs
  within a storm cloud, between a cloud and Earths
  surface, or between two storm clouds.
• It occurs when a spark travels between negative
  and positive charges.

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11.3 Hurricanes

• A hurricane is a tropical cyclone with wind
  speeds of at least 74 miles (119 km) per hour.
• The Saffir-Simpson Hurricane Scale is one scale
  used for rating hurricanes.

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11.3 Tornadoes

• A tornado, like a hurricane, is a system of
  rotating winds around a low-pressure center.
• As the rotating wind pattern narrows and
  lengthens, it forms a funnel cloud.

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11.3 Funnel clouds

• When updrafts in a storm cell reach high speed,
  they begin to rotate.
• As th diameter of the rotation narrows and
  extends downward, a funnel cloud takes shape.

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Investigation 11C
Storms

• Key Question
• How does Doppler radar work?

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Hurricane Hunters

• Why would anyone intentionally fly into the
  driving rain and fierce winds of a hurricane?
  Hurricane hunters know their work saves lives and
  tax dollars.