Adventures in Logophilia Day 2: Downwelling (Jillian)

I've decided to choose these gems at random, because it's more interesting that way instead of going through it all in some semblance of alphabetical order.  This morning, I scrolled through my lists, not sure which word was "calling" me until I happened upon...

Downwelling (noun): the downward movement of fluid, especially in the oceans, the atmosphere, or deep inside the earth's mantle and core. 

Like upwelling, I love this word because of its simple imagery.  Upwelling, they told us in geology class (that was really more oceanology), is when the circulation of the ocean's water comes upward from the ocean floor.  This cycle of upwelling and downwelling is what maintains the temperature of those waters, the cold water coming down (sinking), the warm water coming up (rising).  One of the main fears about global warming is that if the temperature of the oceans is warm enough, the welling stops for a time.  It stops and the oceans eventually get colder.  They get colder, and the rest of the Earth gets colder.  So, global warming would lead to a global freeze, an ice age.  Or, worst case scenario, a snow-ball planet.  But that is again, how I understand it, which isn't very well.  Take this with a grain of salt, but keep the imagery in mind.

To me downwelling and upwelling, could also describe one rising to the surface or delving deep.  It is a lovely metaphor, physical movement to set the mood or direction one is going towards in life, whether good or bad.  Upwelling as a positive, optimistic course.  Downwelling as determination and bravery in the midst of darkness, going deep to confront problems or life in general at the core.  Downwelling is not sinking.  Whatever goes down, of course, must and will rise up again.