Our Planetary System The Earth Planetary Data Orbital
Our Planetary System The Earth
Planetary Data �Orbital semimajor axis • 1. 00 A. U. (1. 5 x 108 Km) �Perihelion • 0. 98 A. U. (1. 5 x 108 Km) �Aphelion • 1. 02 A. U. (1. 5 x 108 Km) �Mean orbital speed • 29. 79 Km/s
Planetary Data � Mass • 5. 98 x 1024 Kg � Equatorial radius • 6378 Km � Mean density • 5220 kg/m 3 � Surface gravity • 9. 80 m/s 2 � Axis tilt • 23. 5 o � Mean surface temperature • 290 K � Number of moons • 1
Earth’s Structure • Continental crust: depth of 0 -75 km • Oceanic crust: depth of 0 -10 km • Upper mantle: depth of 10 -400 km • Transition region: depth of 400 -650 km • Lower mantle: depth of 650 -2, 890 km • D" layer: depth of 2, 700 -2, 890 km • Outer core: depth of 2, 890 -5, 150 km • Inner core: depth of 5, 150 -6, 370 km
Earth’s Atmosphere v. Troposphere: 0 ≈ 12 km v. Convection v. Stratosphere: 12 ≈ 48 km v. Ozone v. Mesosphere: 48 ≈ 80 km v. Ionosphere: above 80 km v. Above 100 km ionize the Sun’s radiation spectrum
The Ozone Layer �Ozone • Absorbs incoming solar ultraviolet radiation, radiation converts ozone (O 3) into O 2 �CFCs • Accumulate in the atmosphere �Broken down by sunlight and converted into chlorine �Chlorine reacts with ozone to create oxygen �( C + O 3→ O 2 + CO) �Carbon continues to react with ozone. One carbon atom can react with up to 100, 000 ozone molecules
Ozone depletion
Surface Heating �Sun’s radiation • Visible light and near-infrared radiation �Earth radiates heat (black body) • Perfect black body 250 K (-23 o. C) �H 2 O & CO 2 trap some 290 K �Greenhouse effect
Greenhouse Effect �Magnitude of greenhouse effect is sensitive �Greenhouse gases • CO 2, H 2 O, Methane �CO 2 increased 20% in last century �Continue to rise 4% each decade
What do you think? 1. 2. The sky is blue because it reflects the color of the ocean. The ocean blue because it reflects the color of the surrounding sky. : 15
Why is the Sky Blue? �Light is scattered by molecules in the air �Rayleigh Scattering �Blue light 400 nm �Red light 700 nm �Blue λ closer in size to air molecules � Scattering by molecules α 1/λ 4
Why is the sky blue? �Example • Blue λ = 400 nm • Red λ = 700 nm • In Rayleigh Scattering �(700/400)4≈9. 4 �Blue light scatters almost 10 times more efficiently than red light
Sunsets Very few atmospheric particles Dense atmosphere Larger particles Dust, ash, & salt particles
Earth’s Interior �How do we know what we know?
Section Review � What is Rayleigh scattering? What is the most noticeable effect for us on Earth? � How do geologists use earthquakes to obtain information about Earth’s interior? � Compare P-waves and S-waves, and explain how they are useful to geologists? � What is the greenhouse effect, and what effect does it have on Earth’s surface temperature? � Give two reasons geologists think that part of Earth’s core is liquid.
- Slides: 17