2.3 Biogeochemical Cycles of the Green World (Planet Earth)
37
Mountain Everest is the highest mountain on the planet, reaching more than
8840 m in height. However, one wonders what processes of the water cycle
are at work at a place where there is no liquid water. The mountain is cold
most of the time. At more than 29,000 feet, temperatures at the mountain’s
peak are quite low, hence making it difficult to rain (Yang et al. 2011).
However, it does get some snow. Snow melts but rarely goes above freezing.
With this in mind, how do you think that snow accumulates forever on the
mountain? As the figure at the end of the case study highlights, winds blow
large amounts of snow from the peak. The sublimation process is functioning.
In the same way, evaporation converts liquid water into vapor, sublimation
converts frozen water into vapor gas, thus bypassing the melting phase. The
heat of the sun also causes sublimation, and on top of the mountain on
any clear day, the sun is quite intense and offers energy for sublimation
despite being below freezing. However, sublimation does not happen at the
peak of the mountains. In case snow is present and ice accumulates in
your neighborhood, sublimation is also happening on a dry and sunny day.
Mountain Everest loses snow because of sublimation.
2.3.1.4 Step 4: Precipitation
Precipitation refers to the several forms of water present within the atmosphere,
typically falling in the form of sleet, hail, and rain. After condensation, the size of
water droplets becomes larger as more water particles meet each other. The force
of gravity is higher than the wind holding it, causing the water to fall in the form
of rain, sleet, hail, or snow (Barry and Chorley 2009). Particulate matter plays a
fundamental role in the development of water droplets. They act as a nucleus where
the water will settle. It is the reason rainwater is not often pure since it can contain
several minerals. The water quantity falling from the sky varies significantly. While
some regions always have rain, others have very little.
2.3.1.5 Step 5: Transpiration
Soil absorbs some of the water from precipitation leading to the transpiration
process. It is similar to evaporation, but the main difference is that water is released
from plant leaves. Plant roots first absorb water and push it towards the leaves. The
water then moves through the plant by capillary action. This water goes through the
transpiration process, which entails its evaporation from flower petals and leaves
(Barry and Chorley 2009). It should be noted that only the extra water that has not
been used for photosynthesis moves out through the stomata. Water then gets into
the biosphere as a gaseous state.
37
Mountain Everest is the highest mountain on the planet, reaching more than
8840 m in height. However, one wonders what processes of the water cycle
are at work at a place where there is no liquid water. The mountain is cold
most of the time. At more than 29,000 feet, temperatures at the mountain’s
peak are quite low, hence making it difficult to rain (Yang et al. 2011).
However, it does get some snow. Snow melts but rarely goes above freezing.
With this in mind, how do you think that snow accumulates forever on the
mountain? As the figure at the end of the case study highlights, winds blow
large amounts of snow from the peak. The sublimation process is functioning.
In the same way, evaporation converts liquid water into vapor, sublimation
converts frozen water into vapor gas, thus bypassing the melting phase. The
heat of the sun also causes sublimation, and on top of the mountain on
any clear day, the sun is quite intense and offers energy for sublimation
despite being below freezing. However, sublimation does not happen at the
peak of the mountains. In case snow is present and ice accumulates in
your neighborhood, sublimation is also happening on a dry and sunny day.
Mountain Everest loses snow because of sublimation.
2.3.1.4 Step 4: Precipitation
Precipitation refers to the several forms of water present within the atmosphere,
typically falling in the form of sleet, hail, and rain. After condensation, the size of
water droplets becomes larger as more water particles meet each other. The force
of gravity is higher than the wind holding it, causing the water to fall in the form
of rain, sleet, hail, or snow (Barry and Chorley 2009). Particulate matter plays a
fundamental role in the development of water droplets. They act as a nucleus where
the water will settle. It is the reason rainwater is not often pure since it can contain
several minerals. The water quantity falling from the sky varies significantly. While
some regions always have rain, others have very little.
2.3.1.5 Step 5: Transpiration
Soil absorbs some of the water from precipitation leading to the transpiration
process. It is similar to evaporation, but the main difference is that water is released
from plant leaves. Plant roots first absorb water and push it towards the leaves. The
water then moves through the plant by capillary action. This water goes through the
transpiration process, which entails its evaporation from flower petals and leaves
(Barry and Chorley 2009). It should be noted that only the extra water that has not
been used for photosynthesis moves out through the stomata. Water then gets into
the biosphere as a gaseous state.