Introduction to the Atmosphere The air around us.

What is the atmosphere? The Earth is surrounded by a blanket of air, which we call the atmosphere. It reaches over 560 kilometers (348 miles) from the surface of the Earth, so we are only able to see what occurs fairly close to the ground. This “blanket” moderates temperature, protects us from harmful radiation and supports life.

Composition of the Atmosphere The present composition of the atmosphere is: 21% OXYGEN (O2) 78% NITROGEN (N2) 0.04% CARBON DIOXIDE (CO2) ~0.9% ARGON (Ar) Besides water vapor, several other gases are also present in much smaller amounts: Carbon monoxide (formula CO) Neon (Ne) Oxides of nitrogen Methane (CH4) Krypton (Kr)

THE FIRST BILLION YEARS The Earth's surface was originally molten, as it cooled the volcanoes out gassed out massive amounts of: CARBON DIOXIDE, STEAM (H2O vapor), AMMONIA and METHANE. There was NO OXYGEN. The STEAM condensed to form water which then produced shallow seas.

Layers of the Atmosphere

The Troposphere Troposphere: The troposphere is the lowest region in the Earth's (or any planet's) atmosphere. On the Earth, it goes from ground (or water) level up to about 11 miles (17 kilometers) high. Weather and clouds occur in the troposphere. In the troposphere, the temperature generally decreases as altitude increases.

The Stratosphere The stratosphere : 11 and 31 miles (17 to 50 kilometers) above the earth's surface. The earth's ozone layer is located in the stratosphere. Ozone, a form of oxygen, is crucial to our survival; this layer absorbs a lot of ultraviolet solar energy. Only the highest clouds (cirrus, cirrostratus, and cirrocumulus) are in the lower stratosphere.

The World’s Highest Skydive!

The Flight of Joseph Kittinger On August 16, 1960, Air Force Captain Kittinger jumped from an open gondola suspended from a giant helium-filled balloon at 102,800 feet (31,300 meters) in the Project Excelsior III flight. The goal of the Excelsior program was to develop a parachute by which a man could survive escape at extreme altitudes. The ascent, through temperatures that fell to 94 degrees below zero, took an hour and a half. Failure of his life-support system above 60,000 feet would have meant almost instant death. With that and other hazards in mind, he stepped out of the gondola and plunged through the stratosphere, reaching supersonic speed somewhere between 614 - 714 miles per hour. Between 90,000 and 70,000 feet, he experienced great difficulty in breathing. At about 50,000 feet, his free-fall speed had dropped to 250 miles an hour in the denser atmosphere.

Project Excelsior III After he had fallen for four minutes and 37 seconds, Kittinger's main chute opened, and some eight minutes later he landed at the White Sands Missile Range in New Mexico with no permanent injuries but with three world records; the highest open-gondola balloon ascent, the longest free-fall, and the longest parachute descent He was also the first man to go supersonic in free-fall. Kittinger had proved that man could function in near-space and that parachuting from very high altitudes was feasible.

The Troposphere vs. the Stratosphere

The Mesosphere The mesosphere : 31 and 50 miles (17 to 80 kilometers) above the earth's surface Temperatures in the mesosphere drop with increasing altitude to about -100°C In the mesosphere temperatures that quickly decrease as height increases. The mesosphere is also the layer in which a lot of meteors burn up while entering the Earth's atmosphere. From the Earth they are seen as shooting stars.

The Thermosphere Temperature increases with altitude. Due to the Suns energy. Temperatures in this region can go as high as 1,727 degrees Celsius. Radiation causes the scattered air particles in this layer to become electrically charged (see ionosphere), enabling radio waves to bounce off and be received beyond the horizon.

The Ionosphere The thermosphere can be identified in two parts- the ionosphere and the exosphere. Ionosphere: 70 km-640 (about 400 miles = 640 km). It contains many ions and free electrons (plasma). Auroras occur in the ionosphere. The Aurora , or northern lights are a result of particles from the sun coming into contact with the Earth’s atmosphere.

The Exosphere Exosphere: the outermost layer of the Earth's atmosphere. From about 400 miles (640 km) high to about 800 miles (1,280 km). The lower boundary of the exosphere is called the critical level of escape, where atmospheric pressure is very low (the gas atoms are very widely spaced) and the temperature is very low In this region, atoms and molecules escape into space.