Saturday, January 12, 2013

Water Revolutions

Temperature starts revolutions.

Probe any natural phenomena with the 5 Whys. Prepare yourself to leap from the concrete and observable to the speculative and spiritual by the third why.
I keep six honest serving-men
(They taught me all I knew);
Their names are What and Why and When
And How and Where and Who.

— Rudyard Kipling, excerpt from the tale of The Elephant's Child
If you examine any natural phenomena with the 5 Whys, one why is usually down to temperature. Temperature seems to be the engine of flow in much of nature.

Temperature drives change. It starts revolutions.

Fresh Water Lakes
"Who comes to a lake for water and sees the reflection of moon?"
Lake water undergoes a temperature-driven revolution during each seasonal cycle.

During the hottest and the coldest time of the year, lake water temperatures are sharply stratified from top to bottom. On the contrary, during the transitional periods from cold to warm, or from warm to cold, the water temperature in lakes overturns to become well-mixed (i.e., nearly homogeneous from top to bottom).

Seasonal Temperature Profile of a Lake in the Northern Hemisphere

Great Northern Loon
Temperature stratification is experienced by swimmers. During warm months, swimming near the surface, the water is pleasantly warm. Diving down to swim at depth, the water is refreshingly cool.
"When you swim you don't grab hold of the water, because if you do you will sink and drown. Instead you relax, and float."
Alan Watts
The depth where the water temperature changes most rapidly, is the thermocline depth, or metalimnion.

During the coldest months, lakes might ice over. Ice and snow cover reflect incident solar radiation. A cold strata of denser water will overlie the less dense, warmer water below. Stratification foments ripeness for change.

Sunset over the ice of Lake Superior
Cause and effect of the seasonal overturn of lake water is orchestrated by the inter-related properties of water:
  1. Temperature changes density; and
  2. Density changes buoyancy.
The stratification that occurs during temperature extremes is inherently unstable, just as the well-mixed water of the transitional seasons is ripe for stratification.

The revolution is ongoing, repetitious, and sublimely beautiful in its simplicity.