Earth’s Atmosphere Notes to be written, are highlighted in red.

Atmospheric Composition What exactly is Air? Air used to be thought of as a “vital spirit.” All cultures had their own understanding of air, whether it be an element of purity, spiritual energy, a deity, or one of Aristotle’s classical elements (earth, fire, water, air) that everything is made up of. Over 200 years, a number of notable scientists finally gave us a scientific understanding of air. Boyle’s Law: Pressure of a gas tends to decrease when the volume increases. + Charles Law: volume of the gas increases or decreases by the same factor as its temperature  Ideal gas Law: The state of an amount of gas is determined by its pressure, volume, and temperature.

Atmospheric Composition Air is mostly made up of lighter elements that are located above the surface of the Earth. However, it also contains tiny particles that you can see such as dust, smoke, pollen, and ash. Effects of Dust While “dusting” can be a chore or in high concentrations, it is considered a type of pollution, there are good benefits of dust. Benefits of Dust Causes rain and snow (nucleation points) Filters sunlight (reflects sunlight away from Earth) Helps make the sky blue (scattering of light waves)

GoogleEarth view of the most frequent anthropogenic (magenta shading) and natural (yellow shading) dust sources over North America detected from MODIS Deep Blue aerosol products between 2003 and 2009. The sources associated with ephemeral lakes or rivers are shaded in blue. 2012, NOAA study Dust is one of the most abundant aerosols in the atmosphere, and by scattering and absorbing solar radiation, it affects climate. The goal of this study was to detect and quantify anthropogenic dust from satellite measurements. Anthropogenic dust sources are generally related to ephemeral lakes or rivers. This implies that they are sensitive to the hydrological cycle and consequently climate change.

Atmospheric Structure Differentiation, or differences in density, creates layers in the atmosphere.

Atmospheric Layers Where space shuttles orbit Earth. Where weather forms and storms take place. Troposphere Stratosphere Mesosphere Themosphere Where space shuttles orbit Earth. Auroras take place in the Ionosphere, located in the lower region of the thermosphere Where shooting stars blaze. Meteors or rock fragments burn up in this layer. Where the protective ozone layer is located.

The Stratos Jump! Red Bull Stratos was a space diving project involving Austrian skydiver Felix Baumgartner. On 14 October 2012, Baumgartner flew approximately 39 km (24 mi) into the stratosphere over New Mexico, United States, in a helium balloon before free falling in a pressure suit and then parachuting to Earth. Reaching 1,357.64 km/h (843.6 mph)—Mach 1.25—Baumgartner broke the sound barrier on his descent, thus becoming the first human to do so without any form of engine power. Preliminary measurements show Baumgartner also broke two other world records. With a final altitude of 38,969 m (127,851 ft) (23.3884 miles), Baumgartner broke the unofficial record for the highest manned balloon flight of 37,640 m (123,491 ft) previously set by Nicholas Piantanida. He also broke the record for the highest altitude jump, set in 1960 by retired USAF Colonel Joseph Kittinger, who was Baumgartner's mentor and capsule communicator at mission control.

Atmospheric Pressure Air is made up of molecules – therefore, it has mass. Anything with mass is subject to a gravitational force Gravity shapes all atmospheric processes. Density and pressure decrease with increase in altitude. Climbing to an altitude of only 5.5 km where the pressure is 500 mb, would put you above one-half of the atmosphere’s molecules.

Air Pressure/Density The amount of force exerted over a surface area is called air pressure! Air density is the number of air molecules in a given space (volume). Air pressure ↓ as altitude ↑. Air pressure ↓ as water vapor ↑ . (Moist air is less dense than dry air. WHY?)

Measure the Pressure The ordinary pressure of the air surrounding us is 14.7 pounds per square inch. However, this pressure is always fluctuating as the wind blows, or even as an object like a car accelerates. Scientists use a barometer to measure atmospheric pressure.