TEMPERATURE, PRESSURE, AND CLOUD FORMATION

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TEMPERATURE, PRESSURE, AND CLOUD FORMATION

• LESSON 6

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INTRODUCTION

• Weve studied about the uneven heating of the
  earths surface and modeled the movement of air.
  In this lesson were going to investigate how
  water evaporates and condenses, how air pressure
  affects cloud formation and the weather on the
  earth.

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OBJECTIVES

• MODEL AND DESCRIBE HOW WATER EVAPORATES AND
  CONDENSES AND HOW THESE PROCESSES PLAY A PART IN
  CLOUD FORMATION.

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• MODEL AND DESCRIBE THE AIR PRESSURE CONDITIONS
  UNDER WHICH CLOUDS FORM
• ANALYZE WEATHER MAPS
• INTERPRET DATA FROM TABLES IN ORDER TO PLOT THE
  PATH OF A HURRICANE

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GETTING STARTED
LOOK AT THE MAPS SHOWN IN FIGURE 6.1 ON PG. 70
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• A. WHERE ON EACH MAP DO YOU THINK IT IS CLOUDY?
• WHAT DO YOU THINK H AND L ON THE MAPS
  REPRESENT?
• WHAT TYPE OF WEATHER WOULD YOU EXPECT IN AN AREA
  MARKED WITH AN H?
• WHAT TYPE OF WEATHER WOULD YOU EXPECT IN AN AREA
  MARKED WITH AN L?

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LETS INVESTIGATE..

• SOME OF THE CONDITIONS UNDER WHICH CLOUDS FORM

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INQUIRY 6.1OBSERVING EVAPORATION AND CONDENSATION

• WHAT DO YOU ALREADY KNOW ABOUT THE WATER CYCLE
  AND HOW CLOUDS FORM?

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MATERIALS

• 2 CLEAR BOTTLES WITH CAPS
• 1 FLASHLIGHT
• 2 DIGITAL THERMOMETERS
• 1 BEAKER OF HOT WATER
• 1 ICE CUBE

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Lets explore the following question

• How does the temperature of water affect
  evaporation and condensation?
• Record this question in your notebook

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How would construct a test using the materials
listed to answer the question?
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REFLECTIONS QUESTIONS 6.1
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A. What happened to the water in each bottle?

• Cold water nothing happened. It remained
  clear.
• Hot water Fogged up

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B. IN WHICH BOTTLE DID YOU OBSERVE THE MOST
EVAPORATIN AND CONDENSATION?

• MORE MOISTURE FORMED IN THE BOTTLE WITH HOT WATER
  BECAUSE HOT WATER EVAPORATES FASTER THANA COOL
  WATER DOES. HOT WATER EVAPORATED INTO A
  GAS---WATER VAPOR-AND THEN CONDENSED INTO WATER
  AGAIN WHEN IT TOUCHED THE SIDES OF THE COOL
  PLASTIC BOTTLE.

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C. WERE YOU ABLE TO CHANGE THE AMOUNT OF
CONDENSATIN THAT OCCURRED INSIDE YOUR BOTTLE? IF
SO, HOW?

• RUBBING THE SIDE OF THE BOTTLE WITH AN ICE CUBE
  DECREASED THE TEMPERATURE OF THE BOTTLE AND
  CREATED MORE CONDENSATION.
• HOLDING YOUR HANDS AGAINST THE BOTTLE TO INCREASE
  THE TEMPERATURE OF THE PLASTIC SURFACE AND
  EVAPORATE THE CONDENSATE ON THE SIDES OF THE
  BOTTLE.

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HURRICANE FORMATION AND THE WATER CYCLE

• WHY DO HURRICANES DEVELOP OVER WARM, TROPICAL
  WATER NEAR THE EQUATOR?

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Read pg. 72 Hurricane Formation and the Water
Cycle
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• THE WARM WATER PROVIDES AN ALMOST ENDLESS SUPPLY
  OF ENERGY FOR THESE STORMS.
• THE PROCESS AT THE HEART OF HURRICANE FORMATION
  IS THE WATER CYCLE.

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CLOUDS FORM DURING THE WATER CYCLE

• WATER EVAPORATES WHEN THE HEAT ENERGY FROM THE
  SUN IS ABSORBED.
• IT RISES TO HIGHER ALTITUDES WHERE IT CONDENSES
  AROUND PARTICLES SUCH AS DUST AND POLLUTION AND
  FORMS CLOUDS.
• THE HEAT GIVEN OFF DURING CONDENSATION FEEDS
  ENERGY INTO A STORM SYSTEM.

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INQUIRY 6.2MODELING THE EFFECTS OF AIR PRESSURE
ON CLOUD FORMATION

• HOW DOES AIR PRESSURE AFFECT CLOUD FORMATION?

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What are the ingredients for cloud formation?

• Think back to Inquiry 6.1 and the reading
  selection Hurricane Formation and the Water
  Cycle.)
• Heat energy, water, and dust or other particles
  are ingredients for cloud formation.

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B. How could you create these conditions in a
bottle?

• Hot water and smoke can provide the water vapor
  and dust particles.

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C. If you want to test how air pressure affects
cloud formation, how could you create high
pressure in the capped bottle?

• Squeeze the bottle and hold it for 5 to 10
  seconds.

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D. How could you create low pressure in the
bottle?

• Release your handswhich are applying the
  pressurefrom the bottle.

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E. How could you keep track of your predictions
and observations?
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Lets review the procedure!

• Put 100 mL of hot water in the bottle.
• Teachers will introduce a burning punk stick to
  add smoke to your bottle. (Look at figure 6.3)
  Keep the lit punk inside the bottle for about 3-5
  seconds. Quickly cap the bottle when its
  removed.
• Swirl the water inside the bottle to reduce fog.
  Shine the flashlight on the bottle while
  squeezing and holding the bottle.

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• A. WHY DID YOU ADD SMOKE TO THE BOTTLE?
• Smoke provides the dust particles on which the
  evaporated water can condense.

• B. WHAT HAPPENED TO THE AIR WHEN YOU SQUEEZED
  THE BOTTLE?
• Squeezing the bottle compressed the air into a
  smaller area and increased its pressure. High
  pressure evaporated any clouds away.

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• C. WHEN YOU RELEASED THE BOTTLE, YOU CREATED A
  LOW-PRESSURE SYSTEM. DESCRIBE THE AIR INSIDE THE
  BOTTLE WHEN THIS HAPPENED?

• The air expanded, and moisture within the air
  condensed into a cloud, which could be seen in
  the bottle.

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• D. IN YOUR OWN WORDS, DESCRIBE HOW AIR PRESSURE
  AND CLOUD FORMATION ARE RELATED.

• Clouds usually form under low pressure conditions.

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Inquiry 6.3Reading Weather Maps

• Using the weather maps provided, what general
  observations can you make about them?

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• Line up you maps in chronological order.
• 1. Identify the following on your maps
• a front
• a low-pressure system
• a high-pressure system
• 2. In what direction is each system moving
  across the country?

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What causes the weather to move in this way?

• The earths rotation (counterclockwise) and winds
  (the jet stream) are responsible for the movement
  of weather in the United States to generally move
  from West to East.
• Review Student sheet 6.3

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A. What kind of weather is associated with a
high-pressure system?

• Clear skies are often associated with a
  high-pressure system.

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B. What kind of weather is associated with a
low-pressure system?

• Low-pressure areas are often associated with
  cloudy skies, precipitation, and rising air
  currents.

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C. What symbol represents a cold front?

• A blue triangle represents a cold front.
• Hint remember an icicle hanging down from a
  roof.

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What symbol represents a warm front?

• A red semicircle represents a warm front.
• Hint remember the sun over the horizon is warm.

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D. Pick one weather front on a map. What
weather is associated with it?

• Storms or changing weather are near the boundary
  (front) between air masses or in the center of
  low-pressure systems.

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D. Why are the triangles and semicircles on the
symbol for a cold and warm front facing in one
direction? What do you think the direction of
the symbol means?

• The direction of the symbol faces the directin in
  which the front is moving.

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F. How does weather move across the United
States.

• Weather systems tend to move across the United
  States from West to East, often following the
  path of the jet stream.

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Why is it important to know this information?

• It can help meteorologists forecast the weather.
  By seeing where weather systems have been, they
  are better able to predict where they are going.