I am just back from Ecuador and the Galapagos. Many long days and so much to think about. It was an incredible trip!
There is, though, no “spring” on the equator (nor is there “winter,” nor “autumn,” nor “summer”), there is only an astoundingly consistent, year-round, 12 hour day in which the sun tracks, with tiny variations, across the highest arc of the sky…each day…everyday!
In some places on the equator there is no difference between the high and low temperatures of any of the months of the year. In these places much of the vegetation is evergreen and in a constant growth and also in continuously overlapping stages of flowering and fruiting. A single plant may display all of the “moments” of its life cycle every day of the year! In other places on the equator local influences (like winds and ocean currents) generate “seasons” quite different from the “solar seasons” of our temperate locales. These other seasons often have unusual names (like “garua” and “doldrums”) and are typically associated with variations in rainfall (“dry” and “wet” seasons). In these places the plants respond to (or have evolved to anticipate) the seasonal cues of moisture. These plants leaf and flower and fruit in the “wet season,” and shed their leaves (a “fall!”) in the dry. Some places on the equator see “seasonal” arrivals and departures of migrating species, while in other places no seasonal changes in animal numbers or diversity are observed.
But, all of this solar consistency does lead to an important point about March 20 (this year’s first day of spring): this is the date (one of two each year) for our own perfect 12 hour day and 12 hour night. This is the date for the same kind of light/night symmetry seen every day of the year on the equator.
So, on March 20 many things observable on the equator will also be observable here! For example, according to myth (which is dealt with very well on Phil Plait’s “Bad Astronomy” web site (http://www.badastronomy.com/bad/misc/egg_spin.html)), we will be able to stand raw eggs on their fat ends (even on the head of a nail!), an accomplishment that is somehow related to the absence or reduction in the Coriolis effect on the equinoxes when the Earth is halfway between its tipping toward and away from the sun. Our guides in Ecuador, when we visited the Equatorial Park, showed us the same egg standing procedure (and rewarded every steady handed participant with a certificate of achievement!), but their explanation of the Coriolis effect mechanism was mythological (but entertaining).
Other Coriolis effect demonstrations included water circling the drain, and the effect of the equator on muscle strength (Allison, one of our participating students, demonstrates) and on balance. By the way, the demonstrations were all based on the “precise” orientation to their marked equator (which was, unfortunately made prior to the development of GPS technology (Latitude 0.00.00 is 200 yards or so off to the north).
Anyway, on March 20 what we will see is our symmetrical light/dark day. The sun will still be low in the southern horizon, but its steady rise will continue until June 21 (the first day of summer!), and our days will continue to lengthen in their daylight “halves” up until then. Our ecosystems (and ourselves?) are tuned to these fluctuating solar seasons, to the changes in daylight lengths, to the changes in temperature, and to the change in the changes all around us, I think! Our trees are starting to flower in response to the lengthening light periods, our birds are releasing the hormones that control their reproductive behaviors and cycles, and my turtle is slowly waking up from his winter torpor. All because there is more and more minutes of light in each single, passing day!
On the equator the consistency of the sun (every day… every month… all year!) might remove it from an organism’s (or a person’s?) biological awareness altogether. I would hate to lose awareness of that first perfect day of spring! I would hate to lose the exhilaration of the steadily warming weather!
It was really nice, though, to feel so warm after this long, cold winter. It was really nice to feel the sun baking down on my head and neck (and feeling it frying up all of those little exposed places around the straps of my sandals). So, pass the sunscreen….spring (and then summer) are coming!
More to come next week! Also, a Galapagos slide show in two weeks or so!