Question

How do sunlight and wind currents affect the hydrologic cycle? How do these effects change with latitude and altitude?

Answer 1

Water vapor is transported by wind to the atmosphere. When the air cools, the water vapor condenses and falls to the Earth. It can be absorbed by plants; stored on the surface in a lake, river, stream, or ocean; evaporation occurs due to the sun light and wind flow. Water on the ground surface can rejoin the atmosphere through evaporation and transpiration by plants. Evaporation and transpiration—known collectively as evapotranspiration - occur during times of dry air, sunshine, or high temperatures and wind. At the high temperature and wind flow, evapotranspiration rate increased. In addition dry air also affect this process.

Temperature drops roughly 6.4 degrees Celsius for each kilometre of altitude gained under normal conditions. Wind speed changes according to altitude as well, increasing where temperature increases. However, it does it not linearly but according the power law wind speed functions. Friction makes the wind about 30% slower at the surface. As latitude increases, the sun shines more obliquely and provides less warming energy. The equator always faces the sun directly and climate is warm year around. The wind velocity at a certain altitude can vary constantly with latitude. With a geostrophic wind pressure gradient force (PGF) is balanced by coriolis force:
PGF = coriolis and coriolis = 2??VsinLat where ? = rate of rotation of the Earth, ? = air density and V = wind speed.
So, V = PGF/ 2??sinLat
If ? and ? are constant V varies inversely with the sine of latitude. Therefore as latitude increases wind speed decreases for a given pressure gradient.