Ch 15 1 Atmosphere Andie
Transcript of Ch 15 1 Atmosphere Andie
Do we have a cold climate in Georgia?
Do we have a dry climate in Georgia?
How would you describe our climate?
• thin layer of gases surrounding the Earth
• no well-defined upper boundary – just fewer and fewer atoms
• density decreases with altitude because number of atoms decrease
What is the atmosphere?
View of the atmosphere from the space shuttle
Air PressureAir Pressure
• atmosphere – exerts pressure
• Why? Because the atoms have weight.
• Gravity holds it on the Earth
•Pressure is higher near surface because more atoms pressing from above.
•sea level pressure = 15 lb/in2
Think about air pressure as being a stack of books.
Here at the surface of the earth, we have more air “stacked” on top of us. That means we feel more pressure than if we were higher in the atmosphere.
http://curriculum.calstatela.edu
Air pressure is measured using an instrument called a barometer.
http://www.dkimages.com/
Notice that it looks like a thermometer. But is does not measure temperature. It measures pressure in inches. (see page 510 in your book)
Also notice that there are words around the gauge. There must be a connection be weather and pressure!
Cold air is more dense (has more pressure) than warm air.
Dry air is more dense than wet air. Notice on the dial that rainy weather has a lower pressure!
Composition of AtmosphereComposition of Atmosphere
atmosphere is a mixture of gasessolid particles
water droplets
Small changes are always happening
N2: nitrogen 78%
O2: oxygen 21%
This means that most of what you breath is NOT oxygen!
• lesser amounts of other gases
Permanent Gases – they are always in the air!
• Water vapor (H20) – can change by the minute!
• Carbon Dioxide (CO2)
• Ozone (O3)
Variable Gases – This means the percents are always changing.
source of this gas: evaporation from Earth’s surface
• water cycle – moves water between oceans, land and atmosphere
• 75% Earth’s surface covered by some form of water
Water Vapor
This satellite image shows the relative amounts of water vapor: Dark – low water, white – high water vapor
•sources: respiration, organic decay, volcanoes, natural and man-made caused fires, burning of fossil fuels.
•important Greenhouse gas
•More Carbon dioxide means more heating of the Earth
Carbon Dioxide (CO2)
What do you think this graph is telling us about the amount of carbon dioxide in the air year by year?
OzoneOzone (O(O33))
• consists of 3 O atoms (O2 + O = O3 )
• highest concentration in stratosphere
•shields surface from UV radiation
•It is good for us up in the stratosphere but bad at the surface where we are.
Why? Because it forms smog – a type of air pollution.
Video clip on ozone
Solids in the atmosphere
• small solid particles put in the air by nature or humans• examples: volcanic ash, salt in sea spray, pollen from plants, and ash from burning vegetation or fossil fuels
Pollen
http://learningoasis.org/mrmc
Dust particles from combustion
Copyright © Michael Collier
We just discussed many of these. Some are natural and some are manmade.
Two common results of pollutants in our atmosphere arephotochemical smog and acid rain.
http://science.kennesaw.edu
It is formed by sunlight causing reactions between chemicals in the air. Most of those chemicals come out of our cars and busses.
Photo taken of Atlanta smog. Notice the brown haze in the sky. That is smog! In Georgia, it is usually caused by car exhaust.
New York smog
http://jmsoul.files.wordpress.com/
Video clip on smog
http://science.howstuffworks.com
Acid rain is caused by water vapor combining with chemicals in the air and forming acid.
The acid rain then changes the water in an area. It can kill trees and poison streams.
http://www.ohiocitizen.org
Video segment on acid rain
Structure of the Atmosphere
• no clearly defined upper limit
• density decreases with elevation
• We divide the atmosphere into layers based on:
Changes in temperature
Layers from Earth’s surface
1) Troposphere
3) Stratosphere
5) Mesosphere
7) Thermosphere
The thermosphere has two parts: ionosphere and exosphere.
Let’s learn a little about each layer!
• lowest layer; temperature decreases with altitude
• thinnest layer (8-16 km, avg. 11 km)
• where weather occurs, where we live
Troposphere
Troposphere – when a cloud reaches the top of this layer, they cannot go higher so they flatten out.
Picture taken by the space shuttle.
Stratosphere
• found above the troposphere
• temperature rises with elevation
• Ozone Layer located here. Remember what we learned about ozone already?
Without the ozone layer protecting us, we could not live on the surface of the Earth!
Mesosphere• above the stratosphere
• temperature decreases with altitude
• Meteorites and space dust burns up in this layer
Thermosphere• above the mesosphere
• temperature increases with altitude
• contains two parts – ionosphere and exosphere
Ionosphere
Quartz Lake State Park, Alaska (Curtis, 1996)
• contains ions: charged particles
• Visible light is given off when ions are hit by energy from the sun. This produces auroras. They are often called northern lights and are seen at night.
http://apod.nasa.gov
Exosphere
The exosphere is the outer part if the atmosphere. Fewer and fewer atoms are found as you get farther from the surface of the earth.
Because of this, there cannot be an actual point where you are no longer in the atmosphere.
Satellites orbit in the exosphere.