Meteorology n The study of the atmosphere.

The Atmosphere n The gases that surround the planet –Much different now than when earth formed. –Early atmosphere had no oxygen.

The Atmosphere n New Atmosphere forms: volcanic eruptions released gases that were trapped inside the earth. n Lighter gases (hydrogen) escaped into space. n Other gases reacted to form second atmosphere

The Atmosphere n Importance of water vapor: –large amounts of water vapor caused torrential rains –precipitation collects to form primitive ocean –some water vapor split into hydrogen and oxygen. (Ozone was produced.)

The Atmosphere n Ozone: O 3 n Collected at about 30 km from surface. n Absorbed most of the UV radiation (harmful). n Made it possible for life to evolve.

The Atmosphere n Life began in waters. n Probably bacteria which released oxygen into the air. n More oxygen producing organisms evolved (Plants). n Some oxygen dissolved into the oceans.

The Atmosphere n Primitive Atmosphere: Carbon dioxide, Nitrogen, Sulfur dioxide, hydrogen sulfide, methane, ammonia n Present Atmosphere: Nitrogen (78%), Oxygen (21%), Water Vapor, Carbon dioxide, Helium, Hydrogen, Argon, & traces of other gases.

Layers of Atmosphere n Troposphere: Closest to Earth n Most weather takes place here n Decreases in temperature with elevation n Tropopause separates troposphere from next layer

Layers of the Atmosphere n Stratosphere: above troposphere n temperature rises with altitude due to ozone absorbing UV radiation & producing heat. n Stratopause seperates stratosphere from next layer

Layers of the Atmosphere n Mesosphere: above stratosphere n temperature decreases with altitude due to distance from the earth. n Mesopause seperates mesosphere from next layer.

Layers of the Atmosphere n Thermosphere: Outermost layer n Solar wind can easily pass through the molecules. n Collisions increase temperature. n Temperature increases with altitude. n Air is very thin n Contains ionosphere

Layers of the Atmosphere n In the thermosphere, collisions due to solar wind causes charged particles, IONS. n This area is called the IONOSPHERE. n Causes AURORAS. (northern lights)

Layers of the Atmosphere n Exospere: outermost layer of the atmosphere n Extends to outerspace n Made of a few light gases

Layers of the Atmosphere

DANGER! n Ozone layer is deteriorating due to chemicals used in refrigerators, air conditioners, and some aerosol sprays. n chlorofluorocarbons n Result may be increase in skin cancer, cataracts, & reduction in diversity of living organisms.

Gravity, Weight, & Air Pressure n Gravity: force that pulls the molecules to the earth. (Strongest near surface.) n Pressure: the weight caused by gravity pulling on all the air molecules above an area. (Strongest near surface) n Measured by: BAROMETER

Gravity, Weight, & Pressure n Air pressure pushes down on surface of mercury in the dish. n Mercury rises in column.

Gravity, Weight, & Pressure n Air pressure decreases with altitude. n On Mount Everest, the atmospheric pressure is less than one-third of what it is at sea level.

Sun’s energy is transferred to Earth 3 ways: n Radiation- energy transmitted through space as waves (electromagnetic spectrum) n Conduction – transfer due to molecules colliding (Must be touching!) A few centimeters is heated this way. n Convection – energy transfer by flow of a heated substance in convection currents.

Radiation 50% of energy is absorbed by surfaces (Dark absorbs more; land absorbs faster than water) 15% absorbed by atmosphere 25% reflected by clouds 6% reflected by atmosphere 4% reflected by earth’s surface.

Convection n Most of the sun’s energy is transmitted this way. n Convection currents cause our weather!

Temperature v. Heat n Temperature – measurement of how fast or slow molecules move. Average energy of all the moving molecules. n Measured by thermometer. n Farenheit, Celsius, Kelvin n Heat – total amount of energy of all the molecules.

Dew Point n Temperature to which air must be cooled to produce condensation. (Can be called condensation temperature.) n Condensation – gas to liquid

Wind n Horizontal movement of air from high to low pressure. High Pressure Low Pressure Wind

Relative Humidity Humidity – amount of water vapor in air Relative Humidity – ratio of water in air relative to how much the air can hold. (expressed as a %) Warm air can hold more moisture than cold air. Measured by a hygrometer (also called a sling psychrometer).

Cloud Formation n Warm air rises and cools n Water condenses on condensation nuclei n May form when air is forced up because of a mountain (orographic lifting) n As air condenses it gives off energy in the form of latent heat

Cloud Types n Classified by height and shape n Cirro- High clouds n Alto- Middle clouds n Strato- Low clouds n Cirrus- “hair” wispy, stringy clouds n Cumulus- “pile or heap” puffy, lumpy clouds n Stratus- layer” sheets of clouds n Nimbus- low, gray rain cloud

Chemical Cycles n Water Cycle: recycles water from earth to atmosphere. n Carbon dioxide-Oxygen cycle: Photosynthesis uses carbon dioxide & produces oxygen. n Respiration uses oxygen & produces carbon dioxide. n Nitrogen is recycled by bacteria.