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Air PressureAir Pressure
Ch. 15Ch. 15
Air Pressure ReviewAir Pressure Review
Air has mass.Air has mass.
Air takes up space.Air takes up space.
Air has density.Air has density.
Air pressureAir pressure is the is the weight of a column of weight of a column of air pressing down on air pressing down on an area.an area.
Atmosphere/PressureAtmosphere/Pressure
Atmosphere held in place by gravityAtmosphere held in place by gravity
Pressure strongest at surface-more air Pressure strongest at surface-more air above youabove you
*as altitude increases, air pressure *as altitude increases, air pressure decreasesdecreases– Stack of booksStack of books– (Volleyball example)(Volleyball example)
Air PressureAir Pressure
As Air Pressure As Air Pressure decreases, so does decreases, so does density.density.
AtmosphereAtmosphere
Atmosphere: a mixture of gases that Atmosphere: a mixture of gases that surrounds Earth: acts like a blanketsurrounds Earth: acts like a blanket– Contains oxygenContains oxygen– Protects from sunProtects from sun
Layers of the AtmosphereLayers of the Atmosphere
Troposphere-we live here, weather Troposphere-we live here, weather happens herehappens here
Stratosphere: ozone layerStratosphere: ozone layer
Mesosphere: “middle layer”Mesosphere: “middle layer”
ThermosphereThermosphere
AtmosphereAtmosphere
Composition of TroposphereComposition of Troposphere
Nitrogen=78%Nitrogen=78%
Oxygen=21%Oxygen=21%
Other 1%=water vapor, CO2 and otherOther 1%=water vapor, CO2 and other
Weather FactorsWeather Factors
Sun’s energy travels to earth as Sun’s energy travels to earth as Electromagnetic waves.Electromagnetic waves.
Weather FactorsWeather Factors
Scattering: Reflections of light in all Scattering: Reflections of light in all directions.directions.
Why is the sky blue?Why is the sky blue?
RadiationRadiation
Sun on your face Sun on your face
standing by campfirestanding by campfire
direct transfer of energy by direct transfer of energy by electromagnetic waves through space.electromagnetic waves through space.
ConductionConduction
Bare feet burned by hot sandBare feet burned by hot sand
direct transfer of heat from one substance direct transfer of heat from one substance to another through direct contact.to another through direct contact.
ConvectionConvection
Basement colder than Basement colder than upstairsupstairstransfer of heat by the transfer of heat by the movement of fluid or air. movement of fluid or air. Hot air rises, cold air Hot air rises, cold air sinks.sinks.
ExamplesExamples
Cooking on the stove-pot on burnerCooking on the stove-pot on burner
Hot air balloon risingHot air balloon rising
Fireplace warming a roomFireplace warming a room
Curling iron on hairCurling iron on hair
Blow dryer on hairBlow dryer on hair
Air from furnace heating the houseAir from furnace heating the house
How is Earth heated?How is Earth heated?
Light/heat from the sun Light/heat from the sun RADIATESRADIATES through the atmosphere, hits the Earth through the atmosphere, hits the Earth where it is absorbed.where it is absorbed.This heats the air above it by This heats the air above it by CONDUCTIONCONDUCTION..This heat rises up to the greenhouse This heat rises up to the greenhouse gases where it is trapped, cools, sinks and gases where it is trapped, cools, sinks and heats at the surface again.-heats at the surface again.-CONVECTIONCONVECTION..
Weather FactorsWeather Factors
Greenhouse EffectGreenhouse Effect
These gases absorb These gases absorb the heat and act as a the heat and act as a “blanket” to keep “blanket” to keep Earth warm.Earth warm.
Some greenhouse Some greenhouse gases: water, gases: water, methane, carbon methane, carbon dioxide.dioxide.
Runaway Greenhouse EffectRunaway Greenhouse Effect
Runaway Greenhouse EffectRunaway Greenhouse Effect
http://www.epa.gov/climatechange/kids/http://www.epa.gov/climatechange/kids/global_warming_version2.htmlglobal_warming_version2.html
Define and DesignDefine and Design
Draw, color, label and explain your own Draw, color, label and explain your own picture of the Greenhouse Effect.picture of the Greenhouse Effect.
Egg in Egg in bottlebottle
Fire warmed up air inside, molecules escaped Fire warmed up air inside, molecules escaped before egg was put on top and when egg before egg was put on top and when egg wobbled.wobbled.
When fire went out, temperature cooled, When fire went out, temperature cooled, molecules condensed, changing air pressure.molecules condensed, changing air pressure.
Since the pressure outside bottle was higher, Since the pressure outside bottle was higher, the higher pressure tried to get in the bottle.the higher pressure tried to get in the bottle.
Since the egg is squeezable, it got pushed into Since the egg is squeezable, it got pushed into the bottle by the air.the bottle by the air.