: Atmospheric Layers and Gases
What two principal gases make up the lower atmosphere?
Nitrogen and oxygen.
Which two gases made up the Earth's very first, thin atmosphere?
hydrogen and helium.
At what altitude (in kilometres) does the troposphere end and the stratosphere begin?
18
What caused these first gases to rapidly dissipate
Solar radiation (when the Sun started to emit sufficient radiation).
Why does the temperature get colder as you go higher in the troposphere?
Because this layer is heated by radiation from the ground.
What natural process formed a new atmosphere after the first one disappeared?
Volcanic activity.
What is the unique feature of the troposphere compared to all other layers?
It is the only layer that has any meaningful weather system.
What biological process in plants releases oxygen as a by-product?
Photosynthesis
Why do temperatures start to rise as you move upwards through the stratosphere?
Because the ozone layer absorbs ultraviolet radiation and generates higher temperatures.
What type of bacteria releases nitrogen as a by-product?
Denitrifying bacteria.