early atmosphere

What was the primary composition of Earth's early atmosphere?

It was primarily composed of:

• Carbon dioxide (CO_2)
• Water vapor (H_2O)
• Nitrogen (N_2)
• Methane (CH_4)
• Ammonia (NH_3)
• Little to no free oxygen (O_2)

How did Earth's early atmosphere form?

It formed primarily through:

• Volcanic outgassing: Gases were released from Earth's interior during volcanic eruptions.
• Comet and asteroid impacts: These celestial bodies delivered water and other volatile compounds.

Describe the conditions prevalent on Earth during the early atmosphere period.

Conditions were harsh:

• High temperatures: Due to intense volcanism and greenhouse gases.
• Absence of an ozone layer: This allowed harmful ultraviolet (UV) radiation to reach Earth's surface.
• Frequent electrical storms.

What was a key event that led to the change in Earth's atmosphere, specifically the rise of oxygen?

The emergence and proliferation of photosynthetic organisms, such as cyanobacteria (blue-green algae), began to release oxygen (O_2) as a byproduct of photosynthesis, gradually accumulating it in the atmosphere over billions of years.