Thursday, July 25, 2013

ciclo hidrológico


Water rules this planet. It regulates temperature, is a major player in trapping heat in our atmosphere, redistributes itself everywhere on the planet as precipitation, and covers the majority of earth's surface in its many personalities (shout out to my southern hemisphere glaciers)
what it do, baby boo Antarctica

The path by which water moves around our pretty blue sphere is called the hydrologic cycle. As the name implies, it's a cycle of hydrated things (e.g. water), that is responsible for the rain in Spain that stays mostly on the plain. 
Spain rain

Ingredients for the earth's hydrologic cycle to cycle hydrologically:
  • A big vast ocean with a WHOLE LOT of water.
  • A big bright source of light and energy
  • Gravity
  • An atmosphere that allows solar radiation (insolation) to get through (light + heat), but traps just the right amount of heat while letting any extra escape**(more on this later)**
  • Land surfaces that water can seep into
  • A substance that can exist as a liquid, solid and gas all within about 100˚ of temperature changes
Things we have on Earth in our modern climate:
    • Oceans!
    • The Sun!
    • Gravity!
    • A nitrogen-oxygen-other-cool-gases atmosphere!
    • Permeable soils and rocks!
    • ~~~~ W A T E R ~~~~~
Water has this incredible ability, unlike most other substances in the universe, that prevents it from changing temperature very easily, called its specific heat capacity. It allows it to absorb a lot of heat before it changes temperature or phase (solid -> liquid -> gas). When liquid water gains enough heat, it evaporates from the surface of the ocean or your armpits as a gas molecule. 
A dramatic interpretation. ~escape~


Usually much less emotionally wracking, evaporation can be undone; the process of condensation occurs through the water vapor's release of energy as heat such that liquid water forms again. The heat that water vapor holds onto until it transitions back to a liquid state is "hidden" as latent heat, but released when the water condenses often to form clouds in the lower atmosphere. When the air reaches a certain saturation point, like a very damp sponge or very pregnant woman, it releases its water. Precipitation is the process of condensed water falling back to earth under the pull of gravity. Precipitation can look like rain, snow, hail, sleet, cats&dogs, etc. 

original artwork by AMWood

This "pilgrimage of water as water molecules" happens on the time scale of days and perhaps months, but is linked to more long-scale circulation systems like the Global Conveyor Belt. 

Image sources:
http://images.aad.gov.au/img.py/65bf.jpg?width=640&height=426
http://spainguides.com/rain.jpg
http://www.chem4kids.com/files/art/matter_evap_2_240.jpg

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