May 2008

OUR WET SEASON IS COMING

 

Some say that in South Florida we have only two seasons:  a cool-dry season and a warm-wet season.  If that is so, the transition between seasons starts in May.  By May even the few trees, like cypress and red maple, that drop their leaves in December have flowered and are now fully in leaf.

 

Up north  "April showers bring May flowers," but in south Florida April has few showers.  Different plants flower in each month of the year. If you keep track you can tell what month it is.  On the other hand we have plants that bloom all year, like elderberry and strangler fig and Spanish needles.

 

At The Refuge in May, pond apple is still in bloom.  If you see creamy petals with a rose colored base floating, look up in the pond apple tree to see the closed blossoms; they never open fully and are thought to be pollinated by beetles.  When the fruit matures it is prized by raccoons though its sweetish custardy taste makes it only passably edible for most humans.  In our marshes pond apple is an important roosting and nesting tree for anhingas, herons, and egrets.  In Australia our pond apple has no natural enemies so it has become a despised invasive weed!  Likewise Australia's Melaleuca has no natural enemies here and is invasive on our Refuge.  I suppose turn-about is fair play.

 

 

Why does our rainy season usually start in May?  Here is the sequence of events.  As it gets hotter, water evaporates; it changes from a liquid to a gas.   So the air becomes more humid.  This warm, humid air rises to high altitudes where it is cooler and forms clouds as some of the water vapor condenses and turns back to a liquid from a gas.  This is like distillation.  Water that condenses on atmospheric particles of dust or sea salt or anything else forms larger and larger drops.  When the water drops get large enough they fall as rain.

 

Wetlands, such as the Refuge and the rest of our Everglades, are part of the rain cycle.  Through evaporation from flowing water and evaporation from plant leaves, wetlands contribute to local rain production.  Wetlands also remove impurities from the water that seeps downward and recharges our drinking water aquifer.  In the past most of the rest of the water flowed south unimpeded as "The River of Grass."  It flowed through the rest of The Everglades to reach Florida Bay.  The water that reaches Florida Bay today still flows to the Atlantic Ocean and the Gulf of Mexico, where it evaporates and is the main source of our peninsular Florida rain.  That is why rainfall is 50% higher along our coasts than in the interior of Florida's peninsula .

 

REVIEW QUESTIONS  

a. The rainy season in south Florida usually starts in May.
b. Rain water is purer than distilled water.
c. Water leaving farmers' fields on the way to The Refuge is purer than rain water.
d. Water that evaporates from our wetlands or farmlands is wasted.