It begins to pour.  You have no umbrella, or printed newspaper.  (The internet, alas, won’t keep your head dry.)  Never mind singing in the rain.  The question is, To run or not to run?

Assuming you’re healthy enough for a mad dash to that building across the street (or the shelter house in a public park), is it worth the energy?  Can you really slip between the drops?  Or will sprinting through a downpour actually make you wetter?

At first glance, the answer appears obvious:  Running means less time spent in the rain, and less-wet clothing.  But the walking advocates have arguments that seem to make sense, too.  If you run through falling raindrops, they point out, you’ll catch more raindrops on the front of your body — chest, stomach, fronts of legs.  If you walk, most of the drops will fall on your head.  Since the front of your body has more surface area than the top of your head and shoulders, you’ll get more water-logged if you run into the wall of rain.

Some have even done mathematical simulations that say you’ll be wetter if you run.  With rain falling straight down from the sky, and no wind, they argue, you’ll scoop up water through the rain field as you dash forward.  But actual experiments with real human beings have found otherwise.

According to physicist Jearl Walker, of Cleveland State University, running keeps you drier because you spend less time being pelted with water.  If there’s no wind, or the wind is blowing toward you, Walker says, you can minimize the number of drops your body encounters by leaning forward, while running as fast as you can.  With a wind at your back, he advises matching your speed to that of the horizontally blowing drops.  Moving with the rain, he says, you’ll avoid both front and back splatters; most drops will strike your head.

And in a 1997 report in the British journal Weather, two climate researchers in Asheville, NC also found that running trumps walking.  On a rainy day, Trevor Wallis and Thomas Peterson suited up in identical sweats, wearing trash bags underneath so that water wouldn’t soak through.  One ran and the other walked through the pouring rain over a 100-meter (328-ft.) course, weighing their track suits before and after their wet dash/stroll.  What they found:  The clothes of Wallis, who ran, were a full 40 percent drier.

If you’re already soaked, or the nearest shelter is very far away, it probably doesn’t matter whether you walk or jog.  To find out if it’s really worth breaking into a run in the rain, physicist Doug Craigen has devised a handy calculator.  You’ll need to enter your height, take some body measurements, and guess at the wind speed of your own rainy day.  Find out how wet you’ll get at   http://www.dctech.com/physics/features/0600.php.

While a tornado would have skipped to the next county and disappeared before you could call it “Ralph,” hurricanes take their sweet time building up their winds, moving towards coastlines and back out to sea at a stately pace. So it’s important to identify these big storms for pilots, ships, and people living in a hurricane’s path.

In the U.S. before the 1950s, hurricanes were identified by latitude and longitude, a system that became confusing when there was more than one tropical cyclone brewing at a time. In the early 50s, the U.S. decided to name storms using the Army/Navy phonetic alphabet, devised for World War II military communications: Able, Baker, Charlie, etc. So in 1952, the news reported on Hurricane Dog, Hurricane Easy, and Hurricane Fox. (If the tropical storm season had been busier, coast-dwellers might have been threatened by Hurricanes How, Item, Love, Sugar, Uncle, X-ray, and Zebra.)

Human beings have a long history of personifying nature (as in Thor, the Norse god of thunder), so using human names for big storms makes sense. Hurricanes that hit the West Indies in the 19th and early 20th centuries were named after saints. And in the 1940s, weather forecasters often gave hurricanes women’s names, like World War 2 fliers naming their fighter planes.

In 1953, the weather service officially switched to women’s names, and in the 1970s, men’s names were added to the mix. Which is why, today, we can be rained on by a hurricane named Richard.

Lists of names are selected for different ocean regions. To make naming easy, there are 6 years of alphabetized lists, which then repeat. In 2008, the first Atlantic hurricane will be named Arthur, the next Bertha. (Names beginning with Q, U, X, Y, and Z are out, since there aren’t enough of them. Which probably pleases the world’s Quentins and Zoes.)

But if your name does happen to match that of a particularly destructive hurricane, you may feel a bit glum until the storms recedes in the collective memory. One of the most memorably destructive tropical storms in history was 2005’s Hurricane Katrina. According to the Social Security Administration, the popularity of the name Katrina for new babies sank from a ranking of 246 in 2005 to 382 in 2006.

Names can often seem silly (it’s hard to take Typhoon Teddy seriously), and some have suggested naming storms only after truly scary people (like Hurricane Hitler). Others have suggested disliked vegetables (Tropical Cyclone Rutabaga), or Hollywood couples (Hurricane Brangelina).

These days, the World Meteorological Organization creates and maintains the rotating lists. Like the team number of a great baseball player, names of the most destructive storms are retired from the roster. In hurricane-heavy 2005, names ran out. So after hurricane Wilma, storms were named for letters of the Geek alphabet: Alpha, Beta, Gamma, Delta, Epsilon, and Zeta.

For a list of names of future tropical cyclones, visit www.nhc.noaa.gov/aboutnames.shtml.

Autumn’s cool days are trimmed with deep blue skies and golden light, and brilliant leaves of yellow, orange and red. Leaves changing color in the fall are a tree’s way of preparing for long winter, rather like we put up storm windows and pull warm clothes and blankets out of storage.

In summer, the leaves on trees like pin oaks and sugar maples are green because they are chock-full of the green pigment chlorophyll.

Trees need sunlight to produce chlorophyll. In turn, chlorophyll uses sunlight’s energy to split water (H2O) into hydrogen and oxygen. Meanwhile, leaves also absorb carbon dioxide gas from the air. The end products of leaf chemistry: carbohydrates (homemade plant food for the tree), and oxygen, released into the air (the gas we need to breathe). The whole process is called photosynthesis.

Along with green chlorophyll, most leaves also contain yellow, orange and red-orange pigments celled carotenoids. Trees don’t need light to make carotenoids. Botanists call them “helper pigments,” because carotenoids absorb some sunlight and (nicely) pass the energy along to chlorophyll. We don’t see much of these deputy pigments (carotene, lycopene, and xanthophyll) in summer, because they are masked by abundant green chlorophyll.

But the ever-shortening days of fall mean less daylight and colder weather. The average tree is rushing to save all the nutrients it can for its winter hibernation. Nitrogen and phosphorus are pulled from leaves for storage in branches. A layer of corky cells grows between the leaves’ stems and their branches, reducing the leaves’ supply of nutrients and water.

With diminished sunlight, water, and nutrients, chlorophyll synthesis slows. Old, worn-out chlorophyll breaks down at the usual rate–ironically, sunlight destroys it–so each leaf’s stock gradually dwindles. And as the green fades, yellow and orange emerge from hiding.

Unlike the green and yellow pigments, red and purple pigments (anthocyanins, part of the flavonoid class) actually form in leaves in the autumn, tinting leaves scarlet and burgundy.

Botanists have long wondered why some trees are genetically programmed to manufacture anthocyanins in the fall. New research indicates that anthocyanins may be a tree’s own sunscreen.

Anthocyanins are made in a leaf’s sugary sap, with the help of lots of sun and cool temperatures. Botanists think that anthocyanins shield the leaves’ fading photosynthesis factories from too much sunlight, rather like the pigment melanin protects our skin from the sun. While the red pigments act as a shield, the tree feverishly breaks down and pulls nutrients out of leaves and into its limbs and trunk before leaves drop or die.

Anthocyanins may also act like Vitamin C or E, scavenging so-called “free radicals” before they can do oxidizing damage to a fall leaf’s fragile structure.

Upper and outer leaves tend to be reddest, since they are most exposed to sunlight and cold. In some trees, like sugar maples, the reds of the anthocyanins combined with the yellows of the carotenoids make especially brilliant orange leaves.

Unfortunately, many insects don’t survive the freezing cold of winter. Others, however, have come up with clever schemes to hang on until spring.

For example, cluster flies sometimes hide out in the nooks and crannies of a warm house or barn over the winter, venturing out to fly around only on milder winter afternoons.

Mosquitoes, like bears, hibernate through the winter cold. Adult mosquitoes look for dark, damp, hiding places–like your basement–to spend their winter vacation. In spring, the females slowly become active, flying around looking for food (fresh blood). Once they’ve had their blood meal, they’re ready to lay eggs, and hatch a new crop to plague us during the summer.

Some mosquito species do things differently. In summer they lay their eggs. The adults die off. But all through fall and winter the eggs lie still, actually freezing when the weather turns nasty. When the warm rains of spring finally come pelting down, the eggs thaw and hatch.

Some water-dwelling insects burrow into lake and river bottoms for the winter, and some beetles hibernate in tree bark. Certain honeybees cram together into a ball, using their wing muscles to generate heat and keep the temperature above freezing in their hive.

Other insects harden themselves to the cold by changing their body chemistry. For example, certain caterpillars in the far north produce a substance similar to car antifreeze, and can survive even when the temperature drops below -100 F. Like birds, some insects migrate in the fall, escaping the cold for warmer places. Locusts are migrators. So are some species of butterflies, moths, dragonflies, ants, termites, bees, wasps, and ladybugs.

The monarch butterfly, the beautiful orange-and-black insect seen in North America in the summer, is one of the most famous migrators. For many years scientists knew that the butterflies took off for the south in cool weather, but no one knew where they spent the winter.

An entomologist named Fred Urquhart spent more than 40 years trying to solve the mystery of migrating monarchs. Urquhart devised a way to tag individual butterflies by attaching lightweight adhesive strips to their wings. He convinced hundreds of people to help him look for the butterflies on their flights. Finally, he was able to narrow the search for their winter resort to the Sierra Madre Mountains in central Mexico.

In January of 1975, when snow covered the summer homes of the monarchs, one of Urquhart’s friends hiked into a 20-acre area of the mountains, and was flabbergasted by what he saw. More than 1,000 trees were covered from top to bottom with a living carpet of monarch butterflies, half-asleep. There were so many butterflies piled onto the trees that limbs sometimes broke under their weight. The mystery of the missing monarchs was solved.

Stories of ball lightning date back to at least the Middle Ages, and scientists estimate that at least five percent of our planet’s population have had the privilege (or, sometimes, the misfortune) to have seen the glowing, floating spheres.

According to eyewitnesses, ball lightning appears as a radiant sphere, ranging in size from a baseball to a basketball. It may be white, yellow, red, orange, or blue, and is usually no brighter than a 100-watt light bulb.

The glowing ball often floats 2 to 6 feet or more above the ground as it travels, sometimes spinning as it moves back and forth, here and there. After seconds—or minutes—the ball goes out with a hiss, pop, or a loud bang. Like a July 4th sparkler, ball lightning may emit an acrid smell like burning sulfur or ozone, and leave smoke behind. Most ball lightning is seen just before or during a thunderstorm, within seconds of a lightning strike.

Millions have seen ball lightning float through windows and screen doors, cut telephone wires, fall into barrels of water with a sizzle. Passengers and crew on an airliner even watched ball lightning float down the aisle after their plane was struck by lightning.

But ball lightning is still an elusive mystery of science – hard to catch on film, with no agreed-upon explanation for how it works. Most ball lightning theories are extremely complicated, involving, for example, standing radio waves in spheres of plasma. But a newer, simpler theory — based in chemistry — seems to explain more of the features of this otherworldly display than have prior explanations. The ingredients for ball lightning, the theory says, are everyday minerals and metals, whipped up by an energizing lightning strike.

The explanation has been developed by John Abrahamson, a chemical engineer who teaches at the University of Canterbury in Christchurch, New Zealand. Abrahamson says that when a bolt of lightning hits the ground, it triggers a chemical reaction between silicon compounds and carbon in the soil. The huge blast of energy with its searing heat acts like a factory smelter, creating pure metallic silicon.

The resulting hot vapor of silicon is composed of tiny particles called nanospheres, each as small as a billionth of a meter. Trailing out of the hole in the ground carved out by the lightning, rising strings of silicon nanospheres form a spinning ring, rather like a cigarette smoke ring. The ring coalesces into a ball of white-hot metal particles, floating through the air like a spherical fog. The ball’s glow is stoked as the silicon particles react with oxygen in the air, keeping the sphere burning bright for seconds or minutes.

Lit from within, the ball drifts through the air, a ghostly apparition. Eventually, like a fire burning down to ash, the ball runs out of silicon to burn, and disappears in a quiet poof. But if its temperature has risen high enough, ball lightning may also go out violently, with a loud bang.