How does water enter the atmosphere?
a.
liquid water evaporates from lakes when heated by the sun.
b.
frozen water sublimates from ice and snow.
c.
liquid water is lost from tree leaves during evapotranspiration.
d.
all of the above.

The correct answer is option d. "All of the above".

Explanation:

Traditionally, it was believed that water enters the atmosphere only by evaporation during water cycle. However, nowadays it is known that water enters the atmosphere by different process. For instance,  frozen water can evaporate directly from ice and snow by sublimation in locations where a temperature below 0 celsius is constant. Additionally, liquid water not only evaporates from lakes, but is also transformed into gas by evapotranspiration from tree leaves or from the grass.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.