The Atmosphere Chapter 22

Atmosphere: A mixture of gasses that surrounds a planet, such as Earth

Chemical composition of the Atmosphere: Gas NameChemical FormulaPercent Volume NitrogenN278.08% OxygenO220.95% *WaterH2O0 to 4% ArgonAr0.93% *Carbon DioxideCO % NeonNe0.0018% HeliumHe0.0005% *MethaneCH % HydrogenH % *Nitrous OxideN2O % *OzoneO % *Atmosphere made up mostly of Nitrogen 78% and Oxygen 21%.

The Earth's atmosphere contains several different layers that can be defined according to air temperature or chemical composition temperature According to temperature, the atmosphere contains seven different layers

1. troposphere - From the surface of the Earth to approximate 11 kilometerstroposphere 75 % of the total mass of the atmosphere is contained in this layer where the majority of our weather occurs.

2. tropopausetropopause an isothermal (temp. not changing) layer in the atmosphere separates from next layerisothermal temperature remains constant and where the jet streams occurjet streams

3. stratosphere.stratosphere temperature increases with altitude because concentration of ozone layer ozone layer The ozone layer is found in this section

4. stratopause - is another isothermal layer of separationstratopause

5. mesospheremesosphere reaches its coldest temperatures (about -90° Celsius)

6. mesopause - is another isothermal layermesopause

7. thermosphere.thermosphere the hottest layer in the atmosphere. Heat is generated from the absorption of solar radiation by oxygen molecules Temperatures can reach 1300 to 1800° Celsius

Earth’s Ozone Layer The ozone layer is a region of concentration of the ozone (O 3 ) molecule in the Earth's atmosphere.ozone layerozone The ozone layer naturally shields us from the harmful effects of the sun's ultraviolet (UV) radiation.ultraviolet (UV) radiation

OzoneOzone is created naturally in the stratosphere by the combining of atomic oxygen (O) with molecular oxygen (O 2 ) destroyed naturally by the absorption of ultraviolet radiation

Human activities are altering the amount of stratospheric O 3. A seasonal thinning of the ozone layer primarily at the South Pole is being called the ozone hole. ozone hole The main agent responsible for this destruction was human- made chlorofluorocarbons or CFCs.chlorofluorocarbons CFCs

Earth’s Solar Budget Earth’s atmosphere affects incoming solar radiation Absorption is defined as a process in which solar radiation is retained by a substance and converted into heat energy. Absorptionheat energy Reflection is a process where sunlight is redirect by 180° after it strikes an atmospheric particle. Reflection

100% of Solar Radiation is sent from Sun 51% makes it to Earth’s Surface This energy is used to heat the Earth's surface and lower atmosphereheat melt and evaporate waterevaporate run photosynthesis in plantsphotosynthesis

49 % does not make it all the way to Earth’s surface 4 % is reflected back to space by the Earth's surfacereflected 26 % is scattered or reflected to space by clouds and atmospheric particlesscatteredreflected 19 % is absorbed by atmospheric gases, particles, and clouds.absorbed

Solar Budget is closely “balanced”. [51% in, 49% out] Too much absorbed or reflected results in Colder temperatures Too much allowed to reach surface results in Hot temperatures Too much “trapped” by Greenhouse gases results in Global Warming

Greenhouse Effect Short wavelength rays can enter the Earth’s atmosphere Outgoing long wavelengths (Infrared heat) cannot escape Water vapor, methane gas, carbon dioxide gases trap heat Volcanic eruptions, fossil fuel burning and other activities add these gases to the atmosphere

Global Warming – global average temperatures steadily increase each year The polar ice caps would begin melting and low land flooding occurs Rainfall patterns change and affects agriculture Weather patterns change and cause major destruction

Measuring Atmospheric Pressure Barometers used to measure atmospheric pressure atmospheres (atm), millimeters or inches of mercury, and millibars (mb).