One hesitates to make a premature pronouncement, but it does appear–at least for the moment–that maybe–and this is only a suggestion, not a prediction, don’t hold me to it–that it could be–although I could be wrong–finally–dare I say it?…spring.
Whew! No blizzard blew in as I typed that, so I think we’re okay for the moment.
Like any other season, spring has all kinds of natural phenomena associated with it, each of which has its own scientific explanation. But the first thing to understand is the change in seasons itself.
We experience seasons because the Earth is tilted on its axis 23.5 degrees, which means that as the Earth orbits the sun, part of the time our hemisphere is tilted toward the sun, part of the time it’s tilted away from the sun, and twice a year it’s not tilted either direction. We call those two occasions solstices, and we just had one a few weeks ago, on March 20. Now we’re getting into the part of the orbit where we’re tilted toward the sun, and each day, we’re tilted a little more in that direction.
Because we’re tilting toward the sun, the sun gets higher and higher into the sky every day, which is why the days are getting longer. As well, the sun’s energy is hitting us a little more directly each day, which means that a little more heat is reaching us every day, which is why the days are getting (slowly) warmer. (Even on some of our recent abnormally cold days you could tell more of the sun’s energy was getting through; though the air temperature was cool, the sun felt warm.)
The first effect we notice around here of the warmer weather is melting. Matter occurs, for the most part, in one of three states: solid, liquid and gas. All molecules of matter vibrate; we call this vibration heat. How tightly the molecules can connect to each other depends on how violently they’re vibrating. If they’re not vibrating very much–they’re cool–they can snuggle up closely and tightly. In water, this happens when the temperature drops below 0 C. The result is ice. As energy is applied–the ever-increasing energy the sun supplies this time of year–and the temperature climbs above 0, the molecules of water begin to vibrate so fast they can no longer stay locked together. They break apart, and the water becomes liquid.
Of course, at night, when the sun sets, this newly liberated liquid frequently freezes again. If that liquid managed to get into a crack in a road surface, or under the road into the soil underneath, it could begin to form another sure sign of spring: potholes. Water has an unusual property, as we discussed a couple of weeks ago: it expands when it freezes, so if it’s trapped under pavement or in a crack, it heaves up the pavement or widens the crack when it freezes, which means the next day even more water can get into that space, and freeze and expand again the following night. Run a car over that weakened spot a few times, and the pavement will collapse or crumble and, presto! a pothole–a sure sign of spring.
Something else we expect in spring in Saskatchewan is wind. April and May are usually our windiest months of the year.
Wind is the movement of air from an area of high pressure to an area of low pressure. Cold air is denser, and therefore has a higher pressure, than warm air, and this time of the year, we’re sandwiched between much colder air masses north of us and much warmer air masses south of us. The result? Whitecaps on our bathwater.
Another sign of spring is the budding of trees–still a few weeks off, but coming soon. Deciduous trees become dormant during the cold, dark months of winter. They drop their leaves to minimize the loss of moisture that would otherwise occur from all that surface area exposed to the icy, dry air. But before they become dormant, they produce buds that contain some or all of next year’s leaves in embryonic form. As the days get longer and the air warms, these buds begin to grow–and soon the tree is back in business for another summer of growth and reproduction.
Ah, reproduction. In the animal world, spring is also a time for the laying of eggs and the having of litters. Humans, too, have a saying that in spring “a young man’s fancy turns to thoughts of love,” although in our case, its more psychological than physiological, since we don’t have chemically-triggered reproductive cycles in the sense that, say, migrating birds have them.
However, we certainly have our own chemical “love-triggers,” and even if they aren’t confined to one particular season, they do seem to kick in more in the spring. That “spark” you feel when you touch the hand of someone special is the start of a flood of chemicals that cause you to flush, to breathe harder, to sweat. That euphoria you feel when you’re spending time with your sweetheart is the result of chemicals your body releases very similar to amphetamines. In fact, you could get roughly the same sensations by coming face-to-face with a bear while taking strong cold medication.
But context, of course, is everything–and in the context of warmer weather, melting snow, singing birds and blue skies, everything seems sweeter–even love.
The wind and the potholes we’ll just have to live with.
