Atmosphere Composition and Layers

Atmosphere Composition

• Homosphere:

  • Characterized by mixed gases; the composition is uniform.

  • Contains approximately 78% nitrogen, 21% oxygen, and 1% other gases.

• Heterosphere:

  • Composed of several distinct layers, each containing different gases.

Atmospheric Regions

• Classified based on temperature profiles.

• Troposphere:

  • The lowest layer.

  • Most weather phenomena occur here.

  • Temperature decreases with altitude.

  • Temperature at the top of the troposphere is about -55 degrees Celsius.

  • "Tropos" means turning, indicating mixing.

• Stratosphere:

  • The second layer of the Earth's atmosphere.

  • Contains jet stream currents reaching speeds up to 400 kilometers per hour.

  • The highest altitude that passenger jets can reach is about 8 to 1 miles (This seems to be a typo and is likely meant to be interpreted individually, either 8 miles OR 1 mile).

• Mesosphere:

  • The third layer of the Earth's atmosphere.

• Thermosphere:

  • The second-highest layer of the Earth's atmosphere.

• Exosphere:

  • The outermost layer of the atmosphere ("Exo" means outer).

  • Gases gradually thin out into interplanetary space.

Key Atmospheric Components and Phenomena

• Ozone Layer:

  • Composed of ozone (O_3).

  • Protects the Earth from harmful ultraviolet (UV) radiation from the sun.

• Ionosphere:

  • Reflects radio waves, enabling long-distance communication.

• Magnetosphere:

  • The magnetic field around the Earth.

  • Van Allen Belts:

    • Protect the Earth from solar winds and radiation.

  • Aurora Borealis (Northern Lights):

    • Occur due to trapped particles near the North and South Poles within Earth's magnetic field.

Ultraviolet (UV) Light

• Source: The Sun

• Effects:

  • Too much UV exposure can cause sunburns and skin cancer.

  • Necessary for the skin to produce vitamin D.

• Vitamin D:

  • Aids the body in absorbing calcium.

  • Example: Vitamin D is often added to milk.

  • Can improve mood.

Greenhouse Effect

• Analogy: Similar to how light passes through greenhouse glass and warms the plants inside.

• Greenhouse Gases:

  • Water vapor and carbon dioxide (CO_2) trap heat from the sun.

  • Water vapor is 3 to 4 times more potent as a greenhouse gas than carbon dioxide.

• Caution: Science-based discussions are crucial for addressing greenhouse gas issues without panic.