Chapter 22 Atmospheric Forces
A total eclipse of the Moon occurs during the night of Wednesday, February 20/21, 2008. • The entire event is visible from South America and most of North America (on Feb. 20) as well as Western Europe, Africa, and western Asia (on Feb. 21). • During a total lunar eclipse, the Moon's disk can take on a dramatically colorful appearance from bright orange to blood red to dark brown and (rarely) very dark gray.
An eclipse of the Moon can only take place at Full Moon, and only if the Moon passes through some portion of Earth's shadow. • The shadow is actually composed of two cone-shaped parts, one nested inside the other. The outer shadow or penumbra is a zone where Earth blocks some (but not all) of the Sun's rays. • In contrast, the inner shadow or umbra is a region where Earth blocks all direct sunlight from reaching the Moon.
During the five millennium period from 2000 BC through AD 3000, there are 7,718 eclipses of the Moon (including both partial and total eclipses). • From 0 to 3 lunar eclipses (partial or total) occur each year. The last time three total lunar eclipses occurred in one calendar year was in 1982. • On average, partial eclipses slightly outnumber total eclipses by 7 to 6.
The last total lunar eclipse visible from the entire continental United States occurred on August 28, 2007. North Americans will have their next opportunity to see a total lunar eclipse on 2010 Dec 21.
Complete the following assignments on your own paper. Number each response clearly as you go.
Chapter 22 page 547 • Section 1 • 1. Preview the chapter by looking at all of the pages of the chapter. • 2. What is the atmosphere?
The layers of gases that surround the earth make up the atmosphere 2. What is the atmosphere?
3. Describe what is found in the atmosphere of Earth and draw the pie graph of the composition of earth’s atmosphere. 78% Nitrogen 21% Oxygen <1% Argon .1% other gases
4. Describe where each of the main gasses come from. • 78% Nitrogen nitrogen cycle • air to • nitrogen in the ground ( by nitrogen fixing bacteria) • then into plants and animals • Then back to the soil by waste products • Bacteria that decay return the nitrogen to the air
Oxygen 21% • Living things ( respiration) and forest fires remove oxygen from the air • Land and ocean plants and algae replace the oxygen by photosynthesis. • The amount used equals the amount produced so.. • The percent • remains 21
5. What factors determine how much water vapor is in the air? • Time of day • Location • Season • Water vapor comes from evaporation of lakes, ocean etc and from transpiration
6. What is ozone? • 7. What does ozone do for us here on earth? How are levels of ozone changed? = O3
7. What does ozone do for us here on earth? How are levels of ozone changed? • Ozone absorbs harmful ultraviolet light • CFC’s break down ozone and weaken the layer that protects us.
Ozone is a colorless, highly reactive gas with a distinctive odor. • It is formed naturally by electrical discharge (lightning) and in the upper atmosphere at altitudes of between 15 to 35km. • Stratospheric ozone protects the Earth from harmful ultraviolet radiation from the sun.
8. What are particulates? Where do they come from? • Solid particles in the atmosphere. • Sources: • Ash • Microscopic organisms • Mineral particles • Pollen • Meteor particles • salt
9. What is atmospheric pressure? • The pressure exerted on a surface from the atmosphere equally in all directions. • We have the pressure of the 80 miles of air above us • which is 15 pounds per square inch.
We don't feel the weight of air • nor do balloons seem heavy. • the same volume, air is lighter than liquid or solids. • But there are many miles of air above us pushing down with incredible weight.
Air gets heavier as it cools. • For example, sometimes rain falling in a thundercloud cools the air fast and the heavy air comes crashing downward about 45 miles per hour.
Atmospheric pressure decreases as altitude increases • Temperature and water vapor also change the pressure.
any time air gets squeezed out from between two objects, they will be held together by air pressure. • If you've ever walked through mud, you noticed how hard it is to lift your feet. That's not because mud is sticky or thick. It's because air gets squeezed out from between your shoes and the mud. Air pressure will try to hold your feet and shoes down.
Drinking through a Straw • One clue to understanding this is to notice what happens to the cheeks of people drinking through a straw.
when you drop your jaw and keep your lips closed, there's more room for the air to spread out. The air molecules are now spread out over a larger volume, so fewer are now striking each square inch of the inside of the mouth; • so the air pressure inside the • mouth is less • This pushes on • the cheeks • causing them • to be sunken.
11. What are the three units used to measure atmospheric pressure? • Atmospheres (atm) • Mm or inches of mercury • Millibars (mb) • Standard atmospheric pressure = 1 atmosphere or 760 mm or 1000 mb
12. What are the two types of instruments used to measure air pressure? • Mercurial barometer Aneroid barometer
14. Briefly describe each of the layers. Troposphere: layer closest to earth, most all weather occurs here, most water vapor and CO2,temp decreases with height 6.5 degrees per km. At 12 km high temp stops decreasing = tropopause
Stratosphere Above tropopause, temp at lowest is -600C temp increases with height and rises to 00C the warmest of this layer represents the stratopause Most all ozone is in the stratosphere
AIRPLANES NOT ALLOWED Very few airplanes can fly as high as the stratosphere because the air is so thin that there is not enough lift to keep the aircraft supported. Some spy planes do fly in the lower stratosphere, such as the U-2 and the SR-71.
Mesosphere and Thermosphere Temp increases steadily! Up to 1,000 0C mesopopause Temp decreases as height increases Average temp -900C coldest in the atmosphere
The situation of having warm air on top of cooler air is referred to as a temperature inversion, because the temperature profile of the atmosphere is "inverted" from its usual state. • Conditions that favor the development of a strong surface inversion are calm winds, clear skies, and long nights. Since the nights in the wintertime are much longer than nights during the summertime, surface inversions are stronger and more common during the winter months.
Normally the air gets cooler as we go higher, • but sometimes the air near the ground is colder than the air above it. • Because cold air is heavier, it will stay close to the ground. • This traps pollutants. • This condition is common in Phoenix in the winter and results in the infamous brown cloud.
Section2 page 555 • 1. What is radiation? All forms of energy that travel through space as waves.
2. What are the forms of radiation found in the electromagnetic spectrum?
3. Draw a diagram of what happens to the solar radiation that hits the earth. P556 absorbed, scattered, or reflected
4. Read the section on Ozone. • What problems would occur if the ozone layer is broken down? • What do we think is responsible for destroying the ozone layer? Damage to DNA and skin cancer would increase CFC’s destroy the ozone
5. What types of things cause the radiation to scatter? • Scattering occurs when particles like clouds , dust, water droplets or large gas molecules present in the atmosphere interact with and cause the electromagnetic radiation to be redirected from its original path.