warm up question do you feel more pressure on your body when you are sitting, standing or lying...
TRANSCRIPT
Warm Up Question
• Do you feel more pressure on your body when you are sitting, standing or lying down? Define pressure and explain.
Water Pressure Demonstration
• Describe what happened indoors.
Describe what happened outdoors.
How much water pressure?
• A two inch diameter pipe that is ten feet long holds 15 pounds of water. If the area of the pipe is 3 square inches, what is the water pressure?
What is the longest length of pipe we could use and still not have the water come out?
Air Pressure and Wind
What is air pressure?
• The force exerted by air molecules
as they collide with a surface• The weight of the atmosphere as it
pushes on Earth’s surface
What is air pressure?
kgkg
• Air has mass• Gravity pulls these
molecules towards Earth giving them weight
• The weight of the molecules acting over an area creates air pressure
What is air pressure?
• At sea level the pressure of air pushing down is 14.7 pounds per square inch
• The weight on the roof of a typical house is about 2.1 million kg (4.6 million lbs)
Why don’t all of our houses collapse? Or Why aren’t we all squished?
CHECK THIS OUT!!!Extreme Atmospheric Pressure
What is air pressure?
• Air pressure is exerted (pushes) in all directions
• An equal force pushing down is balanced by air pushing up
What Is Air Pressure?
1. The same thing as gravity
2. The weight of the atmosphere pushing downward over an area.
3. A form of pollutant
Why Don’t We Get Crushed By The Pressure Of The Atmosphere?
1. The air is not that heavy
2. Air pressure is exerted in all directions, and we are in equilibrium
3. The water in our bodies prevents it
Measuring air pressure
• The barometer is the instrument used to measure air pressure
• 2 types of barometers– Mercury– Aneroid
Mercury Barometer
Measuring air pressure
• As the weight of the air increases, the mercury rises
The pressure of the mercury column must equal the atmospheric pressure at this point, or the mercury will move.
Measuring air pressure
• As the weight of the air decreases, the mercury lowers
Can Barometer
Can Barometer
Measuring air pressure
The Aneroid barometer• A capsule with most of
the air removed changes size as the pressure outside of it increases or decreases
• This moves the needle
Measuring air pressure
• Pressure will be measured in– mm Hg– Inches of Hg– Millibars
• Average Pressure at sea level– 1013.25 mb = 29.92
in. Hg = 14.7 lbs./ in2
Why does air pressure change?
• 3 factors that affect pressure:
– Elevation/Altitude (p414)– Temperature (p416)– Humidity (p416)
Changes inAIR PRESSURE
Humidity Temperature Elevation
Complete the graphic organizer by filling in the 3 factors that affect pressure. Then create branches explaining how they cause pressure to change.
• Recall the towers of water demonstration.
• Draw a mercury barometer in Fullerton, Cuchamonga, and on top of Mt. Baldy. Show the mercury levels to reflect the air pressure at that altitude.
Changes in air pressure
• Altitude
(height above sea level)
As the altitude increases pressure decreases
As the altitude decreases pressure increases
Changes in air pressure
Altitude Drawing
High Altitude / Low Pressure
Low Altitude / High Pressure
Stop Wednesday
Changes in air pressureHumidity
(the amount of water vapor in air)
– Water molecules weigh less than O2 or N2
– Water vapor replaces these molecules in humid air
As humidity increases, pressure decreases
As humidity decreases, pressure increasesHUMID AIRDRY AIR
Changes in Air Pressure
Humidity Drawing
Low Humidity / High PressureHigh Humidity / Low Pressure
Changes in air pressure
Temperature– In warm air the molecules are far apart.– In cool air the molecules are closer together
As air temperature increases, pressure decreases
As air temperature decreases, pressure increases
Changes in air pressure
Temperature Drawing
High Temperature / Low Pressure Low Temperature / High Pressure
Let’s SummarizeDecrease Pressure Increase Pressure
Temperature
Altitude
Humidity
Low Pressure
Generally associated with stormy weather.
The air is rising.
High Pressure
Generally associated with clear skies.
Air is sinking.
Warm Up
• Make the following questions into true statements.
What does a barometer measure?
1. Atmospheric pressure
2. The humidity of the air
3. Air quality
4. How much it has rained
What affects air pressure?
1. Altitude
2. Humidity
3. Temperature
4. All of the above
Why is water vapor less dense than air?
1. There is less of it
2. H2O molecule has less mass than O2 or N2 molecules
3. It is hotter, so it has less mass
Low pressure is usually associated with…
1. Clear skies
2. Cold Desert Nights
3. Earthquakes
4. Stormy weather and rising air
High pressure is usually associated with…
1. Rain
2. Tornadoes
3. Sunny, dry weather with sinking air
4. Pushy car salesmen
Factors Affecting Wind Direction and Speed
What makes the wind blow?
• Air moves from
HIGH PRESSURE to LOW PRESSURE
• This movement of air is WIND
What makes the wind blow? (see last page of note packet)
• Island Example
Sea Breeze- day time
Land Breeze- night time
Stop -Friday
Factors Affecting Wind Direction
• Coriolis Effect
• Pressure Gradients (differences in pressure HIGH vs LOW)
• Friction (resistance)
The Coriolis Effect
• An object moving over Earth’s surface will curve away from its intended path
• This is due to Earth’s rotation– Faster speed at the
equator
– Slower speed at the poles
The Coriolis Effect
• Guidelines (p419):
– objects are deflected to the RIGHT in the Northern Hemisphere and the LEFT in the Southern Hemisphere
– The effect (curve) increases as the difference in tangential speed increases
– The effect DOES NOT depend on the objects direction– The effect is greater at the poles and less at the equator– Most noticeable of large distances (Not in TOILETS)
• Coriolis-1.mp4
The Coriolis Effect
• Let’s Draw!
Low Pressure
Generally associated with stormy weather.
The air is rising.
Pressure Gradients
• Pressure gradient:– A difference in
pressure from one place to another
• Remember wind blows from HIGH to LOW
– The stronger the gradient the faster the wind
– The faster the wind the more curve from the Coriolis Effect
Friction
• Friction between the air and the ground slows wind.
• The higher above the surface the faster the wind will blow
• The higher above the surface the more curve due to Coriolis
Friction• Little friction in the upper
troposphere allows a jet stream to form moving air from west to east.– The jet stream supplies
energy to storms and directs the path of weather across the United States
– Affects airplanes as they travel coast to coast
Jet Stream
Warm Up Questions
What are the 3 factors that affect air pressure?
1. Altitude, Humidity, and Temperature
2. Coriolis, Pressure, Gradients, and Frction
3. Sunlight, Convection, and Friction
How does a pressure gradient affect the speed of wind?
1. The stronger the gradient, the weaker the wind
2. The stronger the gradient, the stronger the wind
3. It does not effect the speed
How does friction affect wind speed?
1. Objects or rough surfaces cause a drag on the wind
2. Friction makes the wind faster
3. Friction creates wind
What are the 3 factors that affect wind direction?
1. Altitude, Humidity, and Temperature
2. Altitude, Humidity, and Coriolis Effect
3. Coriolis Effect, Pressure Gradient, and Friction
Why does the Coriolis Effect cause wind to deflect?
1. The wind was already curving; the Coriolis Effect only effects airplanes
2. The spinning of the Earth causes the path to curve
Convergence- show with your hands
Tuesday Feb 7, 2012
Wed. Feb 8,2012
Global and Local Winds
If winds blow from high to low pressure, won’t they eventually stop?
Thermal Convection on a rotating Earth.
Thermal Convection on a nonrotating Earth.
Trade Winds
Doldrums
Global Winds • Global winds show the general direction the air is flowing throughout the globe.
• Refer to your worksheet for these winds
• The winds are named according to where the wind comes from or originates– Ex. What would the name
of this wind be?
Thermal Convection on a rotating Earth.
Stop to Complete “Global Winds” page.
Global WindsClimate Zones due to
global winds:• Areas of low pressure
are characterized by rising air, precipitation = Rainforest (0°, 60°)
• Areas of high pressure are characterized by sinking air, dry air = Deserts (30°, 90°)
** Add these areas to your worksheet
Warm UpMatching. For each of the following, choose either high pressure or low pressure.
Rising Hot, Humid Air at the Equator
Sinking Dry Hot air at 30 degrees latitude
Rising, Cool, Humid Air the 60 degrees latitude
Sinking, Dry, Very Cold Air at the Poles
Low Pressure
Low Pressure
High Pressure
High Pressure
Draw a large circle to represent Earth
Label the equator. Draw horizontal lines at 30 and 60 degrees latitude
3-Cell Model of Earth’s Winds
Label the high and low pressure belts of the Earth using the previously established reasons.
Sketch in arrows to represent the prevailing winds according the Coriolis Effect. Curve right in the Northern Hemisphere, curve left in the Southern Hemisphere
Label in the ITCZ, Doldrums, Deserts/Horse Latitudes, Temperate Forests, Trade Winds, Prevailing Southwesterly Winds. See 19.3
Continental and Local Winds
• These winds can go opposite the expected global winds due to changes in local conditions:– Continental Winds
• Monsoon
– Local Winds• Sea breeze
• Land breeze
• Santa Ana Winds
Micromonsoon Daytime
Micromonsoon Nightime
Why would the ITCZ shift with the seasons?
Monsoon Wedding
Monsoon
• A Monsoon is a seasonal change in winds.
• Ex. India, North America
Santa Ana Winds
• Occur in Southern California in the late fall/early winter
• A high pressure forms as the desert regions
• As the air sinks it is compressed and usually warms.
Santa Ana Winds
• This creates an offshore wind (blows towards the ocean)
• The air is very dry and often wildfires are a result of this wind
Where will you find areas of high pressure on Earth?
1. North and South Pole Only
2. 0 and 60 Degrees Latitude
3. 30 and 90 Degrees Latitude
4. Over the Ocean
Where will you find areas of low pressure on Earth?
1. North and South Pole Only
2. 0 and 60 Degrees Latitude
3. 30 and 90 Degrees Latitude
4. Over the Ocean
What Creates Santa Ana Winds?
1. High Pressure Over Land and Low Pressure Over Ocean
2. Low Pressure Over Land and High Pressure Over Ocean
3. Politicians In Santa Ana
Label the Pressure and Wind Belts. Label Tropical Forests, Deserts, Temperate Forests.
ITCZ Hot and Humid
Falling Dry Air
Humid Rising Air
Falling Cold, Dry Air
Group Items1 7,8,92 10,113 14,154 4,5,65 12,136 16,177 18,19,208 1,2,39 21,22,23
Group Numbers1 7-9 Hint for 7- see page 420. Draw answer on board.2 16-18 Be prepared to sketch on whiteboard on the map.3 10-12 Draw #11 on the whiteboard6 19-23 Same as group 2.7 13-15 Draw the concept map on the whiteboard8 1-6