Atmosphere

Space Ice The original stellar nebula included water. –Icy grains in protoplanets Half of Earth’s water from came from before the Sun. Bill Saxton/NSF/AUI/NRAO

Oceans Oceans formed from gasses trapped in rocks and collisions from protoplanets. Surface water covers 75% of Earth. –Hydrosphere

Layers of Air The ionosphere includes gases broken into ions: km. The mesosphere has falling temperatures with height: km. The stratosphere is a stable layer of gas: km. The troposphere is a dense, turbulent layer: up to 15 km high.

Blue Sky Air scatters high frequency light more than low frequency light. –Blue light higher frequency than red –Black when no scattered light at night Dust and water increase the scattering – less blue.  Composition of Earth’s atmosphere:  78.08% Nitrogen (N 2 )  20.95% Oxygen (O 2 )  0-4% Water (H 2 O)  0.93% Argon (Ar)  0.04% Carbon Dioxide (CO 2 )

Greenhouse Effect The atmosphere only permits visible light and radio waves. Visible light warms the surface. The surface absorbs visible light and radiates infrared. The infrared is trapped and warms the air. earth atmosphere visible light infrared light

Weather Planetary motion drives the weather. –Seasons from orbit –Day-night temperature –Wind circulation Weather is confined to the troposphere. NOAA – January, 2014

Ozone High frequency UV light forms ozone from oxygen. –Stratosphere, mesophere Ozone concentrates in a layer in the stratosphere. –Opaque to UV-B –Dissolved by CFCs NASA

Magnetic Field The moving iron in the core creates a magnetic field. The magnetic field extends hundreds of kilometers above the surface. Particles from the sun are deflected by the field. earthsolar wind

Aurora Charged particles from the sun can be trapped in the magnetic field. –Concentrated at the poles –Air glows as an aurora NASA, S. Vetter; aurora over Iceland