Tag: the earth and its living world

Ozone in the stratosphere absorbs ultraviolet radiation from the sun, which converts that energy into heat. This process makes the stratosphere warmer by approximately 53 degrees Celsius compared to the temperature at the tropopause.

The Earth is differentiated into the crust, mantle, and core. The crust is the outermost, thin, solid layer of the planet.

The terrestrial planets are the four inner planets of the solar system: Mercury, Venus, Earth, and Mars. They are characterized by their solid, rocky surfaces.

Hydrogen is the most abundant element in the Sun, making up about 73% of its mass. Helium is second at about 25%, with other elements like carbon and oxygen being trace components.

The primary atmosphere of the early Earth was reducing, meaning it contained hydrogen-rich gases like methane and ammonia, and lacked free oxygen.

As the Earth cooled and the atmosphere evolved, atomic gases (which were unstable) and free oxygen (which was highly reactive) were largely absent or consumed in chemical reactions. Both are considered to have been absent or disappeared during the transition.

Cyanobacteria, also known as blue-green algae, were the first organisms to perform oxygenic photosynthesis. This process released oxygen as a byproduct, eventually leading to the Great Oxidation Event.

In the extremely hot, early stages of Earth, the atmosphere consisted of simple atoms like hydrogen, carbon, oxygen, and nitrogen, which had not yet formed complex stable molecules due to the intense thermal energy.

The Oparin-Haldane hypothesis suggests the primary atmosphere was composed of methane (CH4), ammonia (NH3), hydrogen (H2), and water vapor (H2O). These were the precursors for organic molecules.

In the mesosphere, the temperature decreases with altitude because there are very few molecules to absorb solar radiation. It drops from approximately -2 degrees Celsius at the stratopause to about -92 degrees Celsius at the mesopause.