Exploring the Planets: Earth

5 spheres of earth

Atmosphere, hydrosphere, lithosphere, biosphere, magnetosphere

Earth is the only known planet that has life due to…

Liquid water on the surface, stable climate and protective atmosphere

Earliest confirmed life on earth

3.5 Ga

Atmosphere

Retained by gravity and protects earth from UV rays, as well as keeping the climate stable

Primary atmosphere

First atmosphere formed by the earth, made of He and H that escaped easily

Secondary atmosphere

Second atmosphere made by the earth of methane, CO2, SO2 and H2O

Great Oxidation Event

2.4 Ga, enough organisms produced O2 as a waste product that it became 1 weight % in our atmosphere

Early proteozoic

500 million years ago, Earth's atmosphere looked the same as it does today

Abundance of nitrogen in the atmosphere and why?

78%, because it is an inert gas that does not react with anything else

Abundance of oxygen in the atmosphere

21%

Abundance of argon in the atmosphere

0.093%

Trace gases in the atmosphere

CO2, neon, He, CH4

Troposphere

0-12km up, convection cells drive weather and wind, and heat the surface

Stratosphere

12-50km up, temp increases with altitude as it includes the ozone layer, stable and cloud free

Ozone

Absorbs UV rays and splits into O2 and O, releasing energy and heating up

Hole in the ozone layer

Appeared over the Antarctic due to use of CFCs and after they were banned, it has been shrinking

CFCs

Used as coolants and aerosols but free Cl in the atmosphere broke O3 molecules up and made a hole in the ozone layer

Mesosphere

Coldest layer due to lack of ozone, but dense and creates friction with incoming meteors/comets and burns them up

Thermosphere

Upper atmosphere where particles are spaced far apart and absorb lots of UV and x-ray radiation, heating them up to 2000 degrees celcius

Ionosphere

Part of the thermosphere with ionized gas particles that reflects radio waves back around the globe but not GPS signals

Exosphere

Thin layer of He and H and merges with interplanetary space

Region of escape

The exosphere, because particles can speed fast enough to escape earth's gravity

Greenhouse Effect

Sunlight is absorbed at the surface and reradiated back into the atmosphere as infrared thermal radiation, where it is absorbed along with sunlight