Saturday, February 8, 2014

Water's Near Miraculous High Specific Heat Capacity

Which is easier to warm up 100 degrees on the stove: a one pound copper pot or one pound of water in that pot?  It is an interesting question, and one with profound implications for life on Earth.  The answer - copper is much easier to warm than water, because water has a very high specific heat capacity.

Specific heat capacity is a mouthful, but it is just a way of saying that for a given amount of a substance (like water), it takes a certain amount of energy to increase temperature.  Metals like copper have a very low specific heat capacity (copper's is 0.385 J/g to raise the temperature 1°C).   In other words, metals are very easy to heat.  

Water, however, has a very high specific heat capacity (4.184 J/g to raise temperature 1°C).  It resists temperature changes even with large amounts of energy.  This is why on sunny summer day at the beach, the temperature of the air can be quite hot while that water can remain chilly.  This is also why lakes remain warmer than the surrounding air well into the winter.  Because of this delay in the cooling of the Great Lakes, for example, cities from Chicago to Cleveland to Buffalo get a great deal of snow, as precipitation evaporates from the lakes in the beginning of the winter and is then deposited as snow.  

This graphic shows the hydrologic cycle and how the coastal areas have more temperate (and wetter) climates due to the high specific heat of water - From USGS
This high specific heat capacity of water has profound effects (along with ice's decreased density relative to liquid water) on life on earth.  Because water doesn't quickly change temperature, fish don't have to worry about being boiled during a hot day in a river in the desert, and then frozen at night.  

This high specific heat capacity of water is also why areas near coastline have less extremes in their temperatures than areas farther inland.  Water resists changes in temperature, and imparts this resistance to nearby land through slow release of heat and evaporation.

Why is this relevant to planting trees with the Groasis Waterboxx?  The Waterboxx has a large basin which holds around four gallons of water.  This basin surrounds the trunk of the young tree, and prevents the tree from undergoing large swings in temperature between the day and the night.  This can prevent freezing on cold nights, and heat damage during hot days.  This allows trees to spend more time in a temperature range where they can grow.  The Waterboxx basin essentially forms a little coastline right next to the tree, preventing rapid swings in temperature.  

In winter, even though the water inside the Waterboxx may freeze, the Waterboxx's up-sloping design prevents it from cracking.  Once the temperature again reaches above freezing, the Waterboxx begins releasing water to the plant's growing roots.  

The Waterboxx has many more design features garnered from a better understanding of nature (search this blog for some).  It allows you to grow trees where no one thought possible, with no electricity and no irrigation.  It helped 88% of trees (99% when using two trees) survive in a Sahara Desert planting trial, vs. 11% for traditional planting. In the United States, the Waterboxx can be purchased from Dew Harvest.  
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