Summer. Days of pretzels and sodas and root beer. Parasols on a sunny beach. Ice cream meltdown. A smoky haze hangs over the sky.
It all kicks off at cockcrow 94.6 million miles from Earth, where a 35-million-degree nuclear furnace starts hanging out the lights.Ask any school kid if the sun is closer to us in summer or winter and he or she will likely tell you summer of course. But in truth, for us Northern Hemisphere residents, the summer sun must send its electromagnetic waves (light!) packing across 3.2 million extra miles of space before it plunges down into the Earth's atmosphere eight minutes later, agitating electrons, heating things up. The trick is summer sunlight hits down more directly and intensely (instead of at an angle as in wintertime) to put the bloom on the rose and send thermometers soaring.
- EIGHT A.M. Your alarm clock rings. You rub your eyes and head for the shower. Lathering up, you belt out a few old favorite songs from college days. Why do you always sound so good in this watery chamber? Because the sounds bounce around off the close walls and receive a tonal "lift." Electrostatic charge fields created by the splashing water also may add to your wakening sense of well-being.
- 10 A.M. Time to go to the beach. Along the way, oncoming cars creating striking "Doppler shift" sounds as they pass - nnnnnnnnnnnMMMMMMMMMMMeeeewwwwww - the fast-approaching sound waves are "squashed" up to a higher pitch, then they drop rapidly back down as the car passes and starts moving rapidly away (so pronounced you could pinpoint the moment of passing even with your eyes closed).
Summer sunlight dazzles the road and sets up a shimmering "oasis mirage." It looks like water but it's really light from the far edge of the sky that gets bent up toward your eye in the hot layer of air just above the road's surface, which acts like a lens. The shimmering heat adds the illusion of flowing water.
To cut back on glare, you slip on your polarized sunglasses. These have the ability to selectively filter out light that has bounced off surfaces and thus becomes "flattened."
Finally you arrive at the beach and kick the sand as you walk. What is it anyway that keeps you from falling down through the grainy Earth to China? Fundamentally, the sand is made up of electrons speeding about atoms and generating powerful negative charges. These charges push upward on your shoe bottoms (they're full of charges too) and keep you from plunging down through.
You watch waves roll in and wonder why they're parallel to the shore. Why don't they come in at sharp angles? In fact they do try to, but their leading edges get slowed up faster in the shallower water closer in, which allows the angled back edges to catch up, pulling the waves around parallel to the shore.
Down by the beach house, you watch a kid build a sandcastle. He probably doesn't suspect that his delightful creation is held together by atomic and elecrostatic forces, plus water surface tension and sand grains interlocking like jigsaw puzzle pieces.
Farther up the shore a Frisbee slices through the air. It spins like a gyroscopic wing, until it loses energy and plunges into a sunbather's towel. Groggily the woman rolls over in her ultraviolet "shower," then smears on extra lotion to screen out burn wavelengths before going back to sleep.
- HIGH NOON - You don your bathing suit and go for a cooling dip. When you step back out of the water, the breezes bash against the moisture molecules on your skin and start breaking them apart. But this takes energy - heat energy drawn from your body - so you feel refreshed.
Lounging on the beach, you bask in brilliant sunlight that either falls on you directly or hits you on a richochet off the light-colored sands (most intense at midday because now the sun's rays fall straight down through the atmosphere instead of at an angle, thus are filtered less). But watch out! This can cause dilation of and injury to your capillary vessels, followed by
a rush of healing blood - sunburn! More moderate sun exposures tan the skin by activating pigments slowly, which work to screen out offending ultraviolet rays.
Above you see birds on the wing. They're flying in classic V-formation for much the same reason that fish swim in schools and race car drivers tailgate each other: They all enjoy something of a free ride by "hitchhiking" along in the high-energy wake of the leaders. The birds, for instance, gain lift in the trailing updrafts created by the downward wingstrokes of the more forward birds.
You watch huge billowy clouds floating over: Sunlight bounces off their droplets to create a "whiteness" effect. Darker clouds have denser drops that absorb a good deal of the sunlight or reflect it back upward into the sky, away from your eye.
What holds a cloud together? They're not really held together at all, but are more like fountains of condensed water droplets perched atop rising columns of warm, moist air. Watch them for a couple of minutes and you'll see them shift and transform rapidly. As radiated heat lifts off the earth and warms up cloud underbellies, it can cause them to scatter - hence the sky-clearing effects of some summer afternoons.
LATE AFTERNOONS - As you head into the city, you feel it as a sweltering "heat island." - the asphalt and concrete hold the heat a lot longer than woods or open fields. Plus, cars and other heavy machinery are hot, tall buildings block out potentially cooling breezes - you've got an inferno on your hands!
Suddenly, your memory flashes you back to a day in childhood when, feeling hot as blazes in your grandmother's house, you left the refrigerator door open to try to cool down the room. But soon the old overworked motor overheated, making the room hotter than before. (Your Dad, too, got a lot hotter when he found out what you'd done.)
Thinking of oppressive heats reminds you the lawn needs mowing soon. But you know that vigorous exercise in torrid weather can speed blood flow to the skin as the body tries to radiate away excess heat. This can cause a depletion of blood flow to the brain: faintness! You forget the grass for now.
Soon a cooling storm blows in. Thunderclouds are full of churning ice particles that generate electron charges (like scuffing your feet on a carpet). Suddenly, a 100,000,000-volt bolt of lighting climbs in rapid-fire "steps" of 100-200 feet that your eyes, quick as a wink, string together as a single streak of light. (It's really a speeding point of light that lingers in after-images.) The lightening's classic zig-zags are due to deflecting pockets of strong positive charges in the air.
Moments later, cylindrical shockwaves of superheated air - thunder - rumble across the sky for distances of up to 15 miles. Raindrops begin to fall, dropping about 3,000 feet and reaching about 20 miles per hour before aerodynamic drag puts on the brakes. Were it not for this air resistance, gentle summer rain would smash into the ground at speeds upwards of 300 mph.
A dazzling rainbow appears. The prismlike raindrops in the upper atmosphere break up or bend "white" sunlight into its basic spectral colors in forming an enchanted arch across the sky.
How far away is a rainbow? The water drops can be anywhere from only a few yards to a number of miles - its the angle of the sunlight striking them that is important.
Afterward, the sky goes to clear blue again as high air molecules "scatter" more blues than other colors and spread them across the sky. Later, glorious sunset colors appear as low-angled sunlight has to travel through more atmosphere, causing a depletion of blues while leaving striking reds intact.
- DUSK - You drive to a friend's house for a cookout. All around are fireflies: Blink! Blink! Blink! They're oxidizing luciferin molecules in a chemical reaction that's remarkably 100 percent efficient, without heat loss. So it's a cold light for a hot mating purpose.
- 10 P.M. - At home at the end of a long day, you drift out into the back yard for a look at the stars. They appear to twinkle due to heat disturbances in the upper atmosphere.
There's a new moon in the sky, full of bright mystery and charm. What was it the poet said? The new moon holds the old moon in its arms. But how can that be? Why is the dark part of the crescent moon visible at all? After all, it's in the Earth's shadow, isn't it?
The answer is "Earthshine" - small amounts of sunlight bounce back of the Earth's surface and atmosphere to yield a faint illumination to the shadowed part of the moon. Nice!
Weary now from the events of the day, you return inside and pour yourself a cold, refreshing drink. You plop in a few ice cubes and hear them crack and "fry," due to thermal fractures and trapped air bubbles bursting free as the melting begins (similar sounds magnified millions of times are made by icebergs as they melt in their southward drift - called "bergy selzter" by seamen).
Lounging now before the TV's crackling cathode ray tube, you feel your head tip lightly to the side, your EEG brain waves that ordinarily buzz around inside your head at 12 cycles per second begin to elongate, their voltages wavering, the cycles damping down even further until . . . your eyelids are growing heavy now, you . . . suddenly sound asleep.
[Bill Sones is a freelance writer. Jearl Walker, Ph.D., is professor of physics at Cleveland State University.]