Earth's Atmosphere and Geology

Study Notes

The Earth's Atmosphere

The Earth's average global temperature is about 15°C, kept warm by atmospheric gases, without which it would be -20°C.
The early atmosphere, around 4,600 million years ago, consisted mainly of carbon dioxide and water, given off by volcanoes.
Oxygen levels built up slowly, around 600 million years ago, when life exploded on the planet.
Since then, the atmosphere has hardly changed, with nitrogen and oxygen making up 78% and 21% respectively.

The Greenhouse Effect

The atmosphere helps retain energy from the Sun, keeping the Earth's surface warm.
The greenhouse effect is the process by which certain gases in the atmosphere trap infrared radiation, re-emitting it back to the Earth's surface.
This process maintains the Earth's steady temperature, with the Earth and its atmosphere receiving and giving off the same amount of radiation.

The Carbon Cycle

The oceans play a crucial role in the carbon cycle, storing heat and transporting it around the Earth through ocean currents.
The carbon cycle involves the interaction of carbon dioxide in the atmosphere, Marine plants, and dissolved carbon dioxide in the ocean.
Photosynthesis uses carbon dioxide, while respiration releases it, maintaining a balance in the atmosphere.
Human activity, such as burning fossil fuels, is increasing carbon dioxide levels, leading to global warming.

The Rock Cycle

There are three types of rock: igneous, sedimentary, and metamorphic.
The rock cycle links these three types, with igneous rocks forming from volcanic activity, sedimentary rocks forming from erosion and deposition, and metamorphic rocks forming from heat and pressure.
The rock cycle is a continuous process, with rocks being eroded, transported, and deposited, and then transformed into new types of rocks through heat and pressure.

Rock Formation and Weathering

Igneous rocks have a crystal structure, with the size of the crystals depending on the cooling rate of the rock.
Weathering processes, such as rain and freezing, break down rocks, leading to erosion and sedimentation.
Sedimentary rocks form from compacted and cemented sediment, with examples including limestone and sandstone.
Metamorphic rocks form from heat and pressure, with examples including marble and slate.

Description

Learn about the Earth's atmosphere, its composition, and the greenhouse effect. Understand the carbon cycle, rock formation, and weathering processes. Explore the Earth's geology and the different types of rocks.