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Air Pressure

Air Pressure. I can compare and contrast high and low pressure systems. I can describe that high pressure systems result in fair weather due to air sinking, and low pressure systems may result in severe weather due to air rising. Air Pressure Cornell Notes. Inverted Glass Stop the Leak

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Air Pressure

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  1. Air Pressure • I can compare and contrast high and low pressure systems. • I can describe that high pressure systems result in fair weather due to air sinking, and low pressure systems may result in severe weather due to air rising.

  2. Air Pressure Cornell Notes

  3. Inverted Glass • Stop the Leak • Collapsing Can Air Pressure Activities In your notebook: • Diagram of set-up • Description of results • Explanation/principle involved

  4. Air Pressure

  5. Air Pressure • Air Pressureis a measure of the force of the air pressing down on the earth’s surface

  6. Air Pressurecan vary at any particular point on the Earth depending on the density of the air • Density = mass / volume

  7. Title: Activity 1. Inverted Cup Date: Feb. 2010 Summary:

  8. When cup is completely filled with water, no air is left in cup, thus no air pressure. The inverted cup can therefore hold water up because the air pressure is working against the underside of the cup. cardboard Inverted Cup Air Pressure There is higher air pressure outside pushing upward than the inside of cup pushing downward.

  9. Title: Activity 2. Stop the Leak Date: Feb. 2010 Summary:

  10. Title: Activity 3. Collapsing Can Date: Feb. 2010 Explain the principle behind the collapsing can. Summary:

  11. Collapsing Can Before heating, the can was filled with water and air. By boiling the water, the liquid changed into water vapor  The water vapor or steam pushed the air that was inside, out of the can.  In closing off the can, air is prevented from going back to the can.  Cooling (water in basin) condenses water vapor back to water. All the vapor which took up space inside the can turned into a few drops of water, which take up less space.  Pressure inside can drops allowing outside air pressure to push on the can and crush it.

  12. Title: Activity 3. Straw drinking race Date: Feb. 2010 Regular straw Modified straw Explain the principle behind straw drinking. When you drink liquid through a straw, is it accurate to say the liquid is sucked up the straw or pushed up the straw? Summary:

  13. Straw Drinking Race The higher pressure in outside air pushes the liquid up the straw in our mouth The student with the leaky straw cannot create a vacuum above the liquid, so the liquid is not pushed up. Sucking creates a partial vacuum or a lower pressure in straw above the liquid that we drink

  14. Density of Air Density = Mass / Volume  Warm air is less dense than cool air. Warm air rises. Cool air sinks.  Air at high altitudes is less dense than air at lower altitudes.

  15. Factors that affect Air Pressure • Temperature • Water Vapor • Elevation

  16. TEMPERATURE AND AIR PRESSURE Heat= Molecules move faster=molecules move apart, become fewer, weight less=less, low air pressure HIGH (Hot) TEMPERATURE= LOW AIR PRESSURE LOW (Cold) TEMPERATURE=HIGH AIR PRESSURE

  17. AMOUNT OF WATER VAPOR Consists of air and water molecules

  18. Amount of Water Vapor More water vapor means less air molecules= Low Air Pressure Dry air (less water vapor)= High Air Pressure

  19. Measuring Air Pressure Types of Barometer Air Pressure is measured by an instrument called A Barometer • Mercury Barometer • Aneroid

  20. Air pressure increases, column of mercury rises • Air pressure decreases, column of mercury drops

  21. Air Pressure & Weather

  22. High pressure generally means fair weather Air mass in upper atmosphere is sinking (cold, dense air) No clouds Warm, moist air cannot rise Layer of Air

  23. Low pressure generally means cloudy, rainy weather Warm air rises, clouds form Air masses move apart

  24. Weather Map Symbols

  25. Factors Affecting Air Pressure

  26. QUESTIONS – use your knowledge of air pressure to explain the following situations • A falling barometer is followed by several days of rainy weather. • Some people find it hard to breathe at high altitudes. • A rising barometer indicates a spell of cool dry weather.

  27. Air Pressure: Pushing the Weather Homework

  28. Fronts • I can describe the causes and effects (weather conditions) of cold fronts, warm fronts, and stationary fronts.

  29. Air Masses • Air masses are huge chunks air that is the same temperature and density.

  30. What are Fronts? • Fronts happen when 2 different air masses meet BUT they do not mix together • 4 Different Types of Fronts: • Cold Front • Warm Front • Occluded Front • Stationary Front Fronts: Mr Parr Rap Song

  31. How do air masses move? • Cold air (more dense) ALWAYS sinks under warm air (less dense). • So what is the difference between the 4 types of fronts? • Which air mass takes over the other! It’s a battleground. • One air mass is pushing the other out of the way because it does not want to mix! Video on Air Masses: http://www.youtube.com/watch?v=vPC5i6w3yDI&feature=related

  32. Demos: • http://www.classzone.com/books/earth_science/terc/content/visualizations/es2002/es2002page01.cfm?chapter_no=visualization • Lab Demos: • Hot/cold air (via water) demo Hot and Cold Water Demo: http://www.youtube.com/watch?v=Ak9CBB1bTcc&feature=related

  33. Cold Fronts • What happens? A fast moving cold air mass runs into a slow moving warm air mass, pushing the warm air up quickly to form clouds. • Weather forecast: heavy rains and thunderstorms

  34. Cold Front: Weather map symbol • A cold front symbol—The direction that the teeth point indicate the direction the front is moving.

  35. Warm Fronts • What happens? A fast moving warm air mass collides with a slowly moving cold air mass. Warm air slowly moves over the cold air. • Weather forecast: slow steady rain!

  36. Warm front: Weather Map Symbol • Warm Front symbol—The directions that the bumps face is the direction the front is moving.

  37. What types of fronts can you find on the map? In which direction are they moving?

  38. Stationary Front • What happens: A cold air mass and warm air mass meet, but neither air mass has enough force to move the other air mass. • Can sometimes mix together OR will turn into a warm or cold front. • Weather forecast: clouds, rain for multiple days

  39. Stationary Front: Weather Map Symbol Not moving in any direction!

  40. Occluded Front • What happens: • An occluded front happens when a cold front overtakes the warm front in a low pressure storm system. • Weather forecast: Precipitation will diminish and the winds will lessen.

  41. What types of fronts can you find on the map? In which direction are they moving?

  42. Summary of Front Symbols

  43. Practice Reading Weather MapsWhich types of fronts can you find on this map?

  44. What types of fronts are on the map? In which direction are they moving?What type of weather would it produce?

  45. What types of fronts are on the map? In which direction are they moving?What type of weather would it produce?

  46. What types of fronts are on the map? In which direction are they moving?What type of weather would it produce?

  47. Analyze a Map

  48. Front Classification • 1. When a warm air mass moves in on a cold air mass. • 2. When a warm and cold air mass meet, but neither one has enough force to rise over the other. • 3. Brings gentle rains that may last for hours or days. • 4. Strong winds are formed followed by heavy rain, crashing thunder, and flashing lightning. • 5. When the front passes, the temperature warms up and it becomes humid. • 6. When the front passes, the weather turns cooler. • 7. Tornados could occur. • 8. Usually happens and is over with quickly. • 9. Stay in the same area for a long period of time. • 10. When a cold air mass moves in on a warm air mass. 11. Causes warm air to move up slowly • 12. Causes warm air to move up quickly

  49. Interpreting Weather Maps • In groups, complete the interpreting weather maps activity • When finished, work on the “Reading a Weather Map” Worksheet

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