SDUSD Teacher Professional Development - 6th Grade - Earth Science

March 18th, 2009, Mission Bay High School
Presenter - Memorie Yasuda


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The atmosphere and its circulation

Atmosphere basics

placeholder Conditions in the atmosphere
placeholder WebElements™ periodic table
• Printable version
placeholder Ozone in the atmosphere
placeholder Smog
placeholder Greenhouse gases

Where air gets the energy to move

  • Energy from the Sun fuels practically all the motion of air, water and life on the Earth, with the major exception being the motion of plates fueled by energy within the Earth.
  • Energy is emitted by the Sun in the form of electromagnetic radiation that can travel through the near-vacuum of outer space. Sunlight is radiation.
  • When sunlight encounters the Earth and its atmosphere, some of it collides with substances in the air returns to space by reflection, or it is temporarily absorbed and then emitted to space.
  • Radiation absorbed by matter can raise the temperature of substances. That absorbing substance increases its energy.
  • When that same energy is released by matter when it is emitted, energy is lost.
  • There is a general balance between incoming and outgoing radiation to space so that the Earth's surface temperature stays relatively constant over time.
  • The average temperature of the Earth's surface has varied over a small range over time depending on changes in the reflectivity of the Earth, solar output, and concentration of greenhouse gases in the atmosphere.

placeholder Kinds of sunlight that enters the atmosphere and makes it to the ground
placeholder Types of electromagnetic (EM) radiation
placeholder EM and climate:
Global energy budget
placeholder Basic science:
How EM radiation interacts with atoms and atomic groups
placeholder EM and energy:
Solar cells - Optimizing EM absorption and production of electricity
placeholder EM and communication:
How parts ofthe EM are assigned to specific uses such as TV broadcast
placeholder EM and biology
Photosynthesis

How air moves and why

  • Air is mostly heated by the ground.
  • When air is heated, it expands, separates from the ground and rises.
  • As air rises, it encounters lower pressure and it expands and cools.
  • The temperatues at elevation can become cool enough so that water vapor condenses into liquid water. That's how clouds form when moist air rises.
  • As air moves upward, its temperature drops by about 6-10° C per 1,000 m.
  • The average temperature of the Earth's surface has varied over a small range over time depending on changes in the reflectivity of the Earth, solar output, and concentration of greenhouse gases in the atmosphere.

placeholder Concentration of sunlight received at different latitudes
placeholder Explanation of general atmospheric circulation pattern on Earth
placeholder Composite animation with significant features

Clouds and precipitation - where and how they form

  • Clouds are made up of droplets of liquid or frozen water
  • Clouds form when temperature and pressure conditions are just right for water vapor to change into the liquid of solid phase.
  • Clouds form in the sky when air that contains water vapor moves to higher altitude where it is colder.
  • Clouds form in places where air rises. The places where air rises are associated with low atmospheric pressure.
  • Common places where air rises are over the ITCZ just north of the equator, at the polar front, over mountains, in the center of cyclones that are centers of low atmospheric pressure, and over land during the summer when sea breezes and monsoons occur.

placeholder Why air cools as it rises and clouds form
placeholder Clouds continuously forming over the ITCZ
(Give this real-time movie time to load)
placeholder Clouds at the ITCZ and polar front
placeholder Where air rises over mountains
placeholder Annual total rainfall across southern California
placeholder Elevation map of southern California
placeholder Thunderheads forming in the East County
placeholder Air rising as air heats and a seabreeze develops
placeholder Where air rises in a cyclone
NASA satellite images from Katrina, 2005
placeholder Hurricane Emily activity
placeholder Air rising as air heats and a monsoon develops
placeholder Types of clouds

Few clouds and little precipitation - where and how this happens

  • Liquid water vaporizes as temperature rises.
  • When air that contains water vapor moves to lower altitude where it is hotter, clouds tend to vaporize.
  • Clouds tend to disappear in high pressure areas where air falls. This happens near 30 degrees north and south of the ITCZ. San Diego and the Earth's major deserts are at these latitudes.
  • The dry part of monsoons and the dryness of Santa Ana winds depend on this phenomena.

placeholder Santa Ana winds
placeholder Fires

Relevance

San Diego water supply and floods
placeholder Historical map of downtown San Diego
placeholder Location of early weather stations
placeholder San Diego precipitation 1849-present
placeholder Hatfield the rainmaker
placeholder Early dam failures in San Diego

The atmosphere - a personal account while falling through the sky
placeholder Falling through air
Personal account by William H. Rankin
placeholder Falling through a thunderstorm
Personal account by William H. Rankin
placeholder Climbing mountains
placeholder Halo jumping

How different living things deal with conditions at high altitude
placeholder Oxygenation of the atmosphere
placeholder Bar-headed goose
placeholder Himalayas from space
placeholder Countries around the Himalayas
placeholder Map of the world - ETOPO1

How aircraft deal with conditions at high altitude
placeholder No O2, no burning fuel - how high can planes fly?
NEWTON Ask A Scientist©
placeholder SR-71 Blackbird
placeholder No air, no lift - how high can helicopters fly?
NEWTON Ask A Scientist©
placeholder In space where there's no O2 - how do rockets work?
NEWTON Ask A Scientist©
placeholder Ares V rocket

Supporting science

placeholder Coriolis force or effect
placeholder Coriolis activity
placeholder Phase changes - H2O
placeholder Density
placeholder Atmospheric pressure
placeholder Temperature
placeholder Energy
placeholder Work

Questions in science

placeholder Why a filled balloon weighs more than a empty balloon
placeholder Why the curvature of a line on a rotating piece of paper is not exactly like Coriolis deflection
placeholder Getting past the apparent contradiction - that air expands when it's warmed by the ground, and that it also expands as it cools at high elevation

Image credits

Left-to-right and top-to-bottom:
  • Bar-headed goose: Image by World of Oddy.
  • Halo jumping Public domain. U.S. Air force photograph of U.S. Army paratroopers jumping from a C-130, flying 25,000 feet over the Arizona desert. Photo by Master Sergeant Val Gempis. From article by Tech. Sgt. Pat McKenna, 1997, A Bad Altitude. United States Air Force.