The greenhouse and enhanced greenhouse effects refer to the return of approximately percent and greater than percent of the heat radiated by Earth.

The greenhouse and enhanced greenhouse effects refer to the return of approximately 80 percent and greater than 80 percent of the heat radiated by Earth.

Explanation:

During natural greenhouse effect :

. Solar radiation reaches the earth

. Re-radiation of heat occurs

. Less re-emitted heat

. More heath escapes into space

Hence the greenhouse effect refers to return of 80% of heat radiated by Earth.

While during Human Enhanced Greenhouse effect :

. Solar radiation reaches earth

. Re-radiation of heat occurs

. More re-emitted heat

. Less heat escapes into space

Hence the enhanced greenhouse effect refers to return of more than 80% of heat radiated by Earth .

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the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.