CONVECTION CURRENTS IN THE AIR

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CONVECTION CURRENTS IN THE AIR

• LESSON 5

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OBJECTIVES

• SET UP AN INVESTIGATION THAT DEMONSTRATES WHAT
  HAPPENS TO TWO AIR MASSES WHEN THEY MEET.
• ANALYZE THE MOVEMENT OF TWO CONVERGING AIR MASSES
  WITH DIFFERERENT TEMPERATURE AND HUMIDITY
  CONDITIONS.
• DEVISE WORKING DEFINITIONS FOR THE TERMS
  CONVECTION CURRENT AND WEATHER FRONT.

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OBJECTIVES CONTD

• RELATE THE MOVEMENT OF AIR WITHIN A CONVECTION TO
  THE FORMATION OF LAND BREEZES, SEA BREEZES, AND
  TORNADOES.
• EXPLAIN HOW WINDS FORM.

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GETTING STARTED

• Lets recap the results of Inquiry 4.2
  Investigating How Warm and Cool Air Move
• A surface can heat or cool the air above it
• The temperature of air affects the way it moves

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Air Masses

• Where do you think air masses with different
  temperature and humidity conditions are most
  likely to meet in the United States?
• How is this related to the formation of tornadoes?

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INQUIRY 5.1 INVESTIGATING THE EFFECTS OF
COLLIDING AIR MASSES

• WHAT HAPPENS WHEN TWO OF THE SAME --AND THEN
  DIFFERENT--AIR MASSES MEET?

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USING THE GIVEN MATERIALS,

• WHAT ARE SOME POSSIBLE SETUPS?

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POSSIBLE SETUPS

• TWO COLD MOIST AIR MASSES MEETING
• TWO WARM MOIST AIR MASSES MEETING
• A COLD MOIST AIR MASS AND A HOT DRY AIR MASS
  MEETING

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STUDENT SHEET 5.1A

• RECORD THE MATERIALS AND PROCEDURES YOU WILL USE
  FOR EACH OF THESE SETUPS.
• WHAT VARIABLES WILL YOU KEEP CONSTANT?
• WHICH VARIABLE WILL YOU CHANGE?
• RECORD YOUR IDEAS ON YOUR STUDENT SHEET.

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NOW, LOOK BACK AT THE QUESTION AND HYPOTHESIZE.

• I THINK THAT WHEN TWO LIKE AIR MASSES MEET
  ___________________ HAPPENS BECAUSE
  _______________.
• I THINK THAT WHEN TWO DIFFERENT AIR MASSES MEET
  ________________ HAPPENS BECAUSE _______________.

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NOW PREDICT WHAT WILL HAPPEN WHEN YOU
TEST(Record on table 1 of your student sheet)

• SET UP NUMBER ONE WHEN TWO COLD MOIST AIR
  MASSES MEET _______________________________.
• SET UP NUMBER TWO WHEN TWO WARM MOIST AIR
  MASSES MEET _______________________________.
• SET UP NUMBER THREE WHEN A COLD MOIST AIR MASS
  AND A HOT DRY AIR MASS MEET ______________________
  _________.

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KEEP THE FOLLOWING POINTS IN MIND

• KEEP THE CONVECTION TUBES CONNECTED AT ALL TIMES
• DO NOT RECORD ANY TEMPERATURES CHANGES IN THIS
  LESSON
• INTRODUCE SMOKE INTO THE TOP OF THE CYLINDER
  (FIG. 5.2)
• REVIEW THE SAFETY TIPS LISTED NEXT

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SAFETY TIPS

• Roll up loose sleeves and tuck in loose clothing.
  Keep loose hair tied back.
• Do not let the burning punk touch the cylinder.
• Do not ask the teacher to light your candle until
  you are ready.
• Do not reach across an open flame.
• Do not leave the candle under the plastic
  cylinder for longer than 1 minute.

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BEGIN THE INVESTIGATION

• DISCUSS YOUR OBSERVATIONS WITH YOUR GROUP
• RECORD YOUR FINDINGS ON YOUR STUDENT SHEET
• USE YOUR FLASHLIGHT TO SEE THE SMOKE

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CLEAN UP

• PUT OUT THE BURNING PUNK BY DIPPING JUST THE TIP
  IN A CUP OF WATER
• CUT OFF THE WET TIP WITH SCISSORS
• REFILL YOUR CONTAINER WITH CRUSHED ICE FOR TH E
  NEXT CLASS

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REFLECTION QUESTIONS 5.1

• 1.WHAT DID YOU OBSERVE WHEN BOTH TUBES CONTAINED
  AIR WITH THE SAME TEMPERATURE AND HUMIDITY
  CONDITIONS? WHY DO YOU THINK THIS HAPPENED?

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• B. WHAT DID YOU OBSERVE WHEN THE TUBES CONTAINED
  AIR WITH DIFFERENT TEMPERATURE AND HUMIDITY
  CONDITIONS? WHY DO YOU THINK THIS HAPPENED?

THE AIR MOVED QUICKLY THROUGHOUT BOTH TUBES. AIR
IN THE COLD TUBE SANK AND MOVED THROUGH THE
PLASTIC TUBING TO THE WARM TUBE TO REPLACE ITS
RISING, WARM AIR. WHEN THE COLD AIR GOT WARMER,
IT ROSE AS WELL.
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• C. ON THE BASIS OF YOUR RESULTS FROM LESSONS 4
  AND 5, UNDER WHAT CONDITIONS DO YOU THINK WINDS
  AND ROTATING STORMS MIGHT FORM?

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• D. WHERE IN THE UNITED STATES DO YOU THINK AIR
  MASSES WITH DIFFERENT TEMPERATURE AND HUMIDITY
  CONDITIONS MIGHT MEET?
• The central part of the U.S. tornado alley

THE BOUNDARY THAT FORMS WHEN THIS HAPPENS IS
CALLED A WEATHER FRONT. WHAT TYPE OF WEATHER DO
YOU THINK MIGHT OCCUR ALONG A FRONT?
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STUDENT SHEET 5.1B

• ILLUSTRATE HOW AIR MOVED IN YOUR GROUPS
  CONVECTION TUBE
• RELATE THE MOVEMENT OF AIR WITHIN YOUR CONVECTION
  MODEL TO THE FORMATION OF LAND AND SEA BREEZES
• APPLY THE MOVEMENT OF AIR WITHIN YOUR CONVECTION
  MODEL TO THE DEVELOPMENT OF TORNADOES.