Zoom: From Atoms and Galaxies to Blizzards and Bees: How Everything Moves (35 page)

5. The lowest sea-level barometric pressure ever recorded was 24.69 inches, or 870 millibars, in the eye of a typhoon, and the highest was 32.01 inches (1,084 millibars) in Siberia on an exceptionally cold day. More than enough to make your ears pop. Cold air is denser than warm air, and dry air is denser than humid air. Thus cold, dry air has its molecules packed closest together. Altogether, this represents an impressive maximum sea-level variation in pressure of 20 percent. Experiencing that much of pressure change would normally require ascending or descending a vertical mile, as you would if you travel from New Orleans to Denver.

1. Here is a summary of what you experience with each Saffir-Simpson category of hurricane. These descriptions are excerpted from those created by the the Saffir-Simpson team (Timothy Schott, Chris Landsea, Gene Hafele, Jeffrey Lorens, Arthur Taylor, Harvey Thurm, Bill Ward, Mark Willis, and Walt Zaleski) and are used with the kind permission of the National Oceanic and Atmospheric Administration.

Category 1 Hurricane (sustained winds 74–95 mph, or 119–153 km / hr)

Very dangerous winds will produce some damage. This means that older mobile homes could be destroyed and some poorly constructed frame homes can experience major damage, such as the loss of the roof covering and awnings. Masonry chimneys can be toppled. Even the best-made frame homes could have damage to roof shingles, vinyl siding, and gutters. Windows in high-rise buildings can be broken by flying debris. There will be occasional damage to commercial signage, fences, and canopies. Large tree branches will snap, and shallow rooted trees can be toppled. Extensive damage to power lines and poles will likely result in power outages that could last between a few and several days. Hurricane Dolly (2008) is an example of a hurricane that brought category 1 winds and damage to South Padre Island, Texas.

Category 2 Hurricane (sustained winds 96–110 mph, or 154–177 km / hr)

Extremely dangerous winds will cause extensive damage. There is a substantial risk of injury or death to people, livestock, and pets from flying and falling debris. Older mobile homes have a very high chance of being destroyed, and the flying debris generated can shred nearby mobile homes. Newer mobile homes can also be destroyed. Poorly constructed frame homes have a high chance of having their roof structures removed. Unprotected windows will have a high probability of being broken by flying debris. Well-constructed frame homes could sustain major roof and siding damage. Failure of aluminum screened-in swimming pool enclosures will be common. There will be a substantial percentage of roof and siding damage to apartment buildings and industrial buildings. Unreinforced masonry walls can collapse. Windows in high-rise buildings can be broken by flying debris. Commercial signage, fences, and canopies will be damaged and often destroyed. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected, with outages that could last from several days to weeks. Hurricane Frances (2004) is an example of a hurricane that brought category 2 winds and damage to coastal portions of Port Saint Lucie, Florida.

Category 3 Hurricane (sustained winds 111–129 mph, or 178–208 km / hr)

Devastating damage will occur. There is a high risk of injury or death to people, livestock, and pets from flying and falling debris. Nearly all pre-1994 mobile homes will be destroyed. Most newer mobile homes will sustain severe damage, with potential for complete roof failure and wall collapse. Poorly constructed frame homes can be destroyed by the removal of the roof and exterior walls. Unprotected windows will be broken by flying debris. Well-built frame homes can experience major damage involving the removal of roof decking and gable ends. There will be a high percentage of roof-covering and siding damage to apartment buildings and industrial buildings. Isolated structural damage to wood or steel framing can occur. Complete failure of older metal buildings is possible, and older unreinforced masonry buildings can collapse. Numerous windows will be blown out of high-rise buildings, resulting in falling glass, which will pose a threat for days to weeks after the storm. Most commercial signage, fences, and canopies will be destroyed. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for between several days and a few weeks after the storm passes. Hurricane Ivan (2004) is an example of a hurricane that brought category 3 winds and damage to coastal portions of Gulf Shores, Alabama.

Category 4 Hurricane (sustained winds 130–156 mph, or 209–251 km / hr)

Catastrophic damage will occur. There is a very high risk of injury or death to people, livestock, and pets from flying and falling debris. Nearly all pre-1994 mobile homes will be destroyed. A high percentage of newer mobile homes also will be destroyed. Poorly constructed homes can sustain complete collapse of all walls as well as the loss of the roof structure. Well-built homes also can sustain severe damage, with loss of most of the roof structure and/or some exterior walls. Extensive damage to roof coverings, windows, and doors will occur. Large amounts of wind-borne debris will be lofted into the air. Wind-borne debris will break most unprotected windows and penetrate some protected windows. There will be a high percentage of structural damage to the top floors of apartment buildings. Steel frames in older industrial buildings can collapse. There will be a high percentage of collapse to older unreinforced masonry buildings. Most windows will be blown out of high-rise buildings, resulting in falling glass. Nearly all commercial signage, fences, and canopies will be destroyed. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Long-term water shortages will increase human suffering. Most of the area will be uninhabitable for weeks or months. Hurricane Charley (2004) is an example of a hurricane that brought category 4 winds and damage to coastal portions of Punta Gorda, Florida, with category 3 conditions experienced elsewhere in the city.

Category 5 Hurricane (sustained winds greater than 157 mph, or 252 km / hr)

Catastrophic damage will occur. People, livestock, and pets are at very high risk of injury or death from flying or falling debris, even if they’re indoors in mobile homes or frame homes. Almost complete destruction of all mobile homes will occur, regardless of age or construction. A high percentage of frame homes will be destroyed, with total roof failure and wall collapse. Extensive damage to roof covers, windows, and doors will occur. Large amounts of wind-borne debris will be lofted into the air. Wind-borne debris damage will occur to nearly all unprotected windows and many protected windows. Significant damage to wood-roof commercial buildings will occur from the loss of roof sheathing. Complete collapse of many older metal buildings can occur. Most unreinforced masonry walls will fail, which can lead to the collapse of the buildings. A high percentage of industrial buildings and low-rise apartment buildings will be destroyed. Nearly all windows will be blown out of high-rise buildings, resulting in falling glass, which will pose a threat for days to weeks after the storm. Nearly all commercial signage, fences, and canopies will be destroyed. Nearly all trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Long-term water shortages will increase human suffering. Most of the area will be uninhabitable for weeks or months. Hurricane Andrew (1992) is an example of a hurricane that brought category 5 winds and damage to coastal portions of Cutler Ridge, Florida, with category 4 conditions experienced elsewhere in southern Miami-Dade County.

2. The critical fact of cloud birth is that cold air cannot hold as much moisture as warm air. The difference is dramatic. At one hundred degrees Fahrenheit, air can hold ten times more water than it can at thirty-two degrees Fahrenheit. So when warm air rises and cools, there comes a height where it’s cooled to its water-holding limit. At that moment of saturation the invisible vapor turns into untold billions of tiny liquid droplets: a cloud. This is why clouds usually have flat bottoms. That’s the altitude and temperature at which that day’s air reaches its dewpoint. Drier air must rise farther in order to cool enough to be saturated, which explains why clouds are much higher on crisp days than on humid days.

3. An open secret in the forecasting business is that meteorologists love violent weather. This is when all their book training about low pressure and close-together isobars comes alive. A hint of this secret reached public awareness with Sebastian Junger’s 1997 bestseller, The Perfect Storm: people realized that perfect had one meaning for meteorologists and the opposite meaning for everyone else.

1. These speeds assume no air resistance, which adds a bit of imprecision to falling speeds because it varies according to how spread-out you are—e.g., whether you’re plummeting in a dive or with limbs extended, as is taught in skydiving classes. With splayed arms and legs, a falling person travels at forty-two (rather than forty-four) miles per hour after two seconds and sixty (rather than sixty-six) miles per hour after three seconds.

2. The place in the sky around which all the constellations and stars pivot—similar to the stationary leg of the drafting compass we used at school to draw circles—is called the North Celestial Pole. Polaris happens to sit less than one degree from that spot. But thanks to our planet’s 25,780-year axis wobble, this stationary celestial point slowly shifts its location over the centuries and rarely happens to lie within one degree from any naked-eye star. At the time of the ancient Greeks, the star that most nearly didn’t move had just changed from Thuban, in Draco, where the main passage in the Great Pyramid at Giza roughly points, to Kochab, in the Little Dipper. The current polestar, Polaris, is, by chance, the brightest star closest to the North Celestial Pole in the entire twenty-six-millennium precession cycle. Polaris doesn’t seem to budge as the night wears on.

3. A veterinary study of cats that had fallen from high-rise buildings showed that 90 percent of them survived and that 30 percent of those that did had no injury. Mice and squirrels also have nonlethal terminal velocities; the fastest speed of a falling mouse would be just 1 percent of that of a falling elephant, according to physics (not actual experience). In fact, no fatal altitude exists for most small rodents: their terminal velocities are low enough to prevent acceleration to a lethal speed no matter what height they fall from. However, especially in cats, injury avoidance is aided by the ground often being a bit soft. It’s not rocket science to conclude that it’s better to land on a lawn than on a sidewalk.

4. The Greeks disbelieved in nothingness because they were such scrupulous logicians. What do we experience after death? To those who’d say, “We are nothing,” they’d counter that the verb to be contradicts nothingness. To combine “is” or “are” with “nothing” is nonsensical. You can’t “be nothing” any more than you can “walk not walk.” Nothingness is a contradictory, meaningless concept—words without substance. You seem to be saying something, but you’re not. By their reasoning, a vacuum cannot exist. Today we get their logic, it remains flawless, and yet they were wrong anyway. That’s because the real world is not obligated to live by the rules of human language, which relies on symbolism. Actual water is not the word water, and the word it corresponds to nothing at all in the phrase “it is raining.”

5. It remains little known and rarely discussed in Western classrooms today, but there is convincing evidence that ancient Indian astronomers beat out all the Renaissance scientists when it came to discovering gravity’s existence. A full millennium before Newton, in the seventh century, Brahmagupta, living in Rajasthan, said, “Bodies fall towards the Earth as it is in the nature of the Earth to attract bodies, just as it is in the nature of water to flow.” Nor had he merely stumbled on such profundities by guesswork. He was a brilliant mathematician, the person who invented (or perhaps we should say discovered ) the number zero.

Yet even he might not have been first. A century earlier, another Indian, named Varāhamihira, whom we discussed in chapter 8, wrote of a force that might be keeping everything stuck to the earth. This even went beyond the concept of local falling objects; Varāhamihira, critically, recognized that this force applies to the sun pulling on the planets. The very word for gravity in Sanskrit—coined centuries before Newton—is gurutvakarshan, which means “to be attracted.”

6. Here’s why an apple falling off a branch displays the same behavior as the moon. The moon is sixty times farther from Earth’s center than the apple is, and thus it should experience 60 × 60, or 3,600, times less gravity than the apple. So instead of falling at the apple’s rate of twenty-two miles per hour faster each second, it should fall 3,600 times less fast, or just 0.006 miles per hour—about six inches a minute. That’s the speed of dust settling after you’ve shaken out a rug. Thus the moon barely falls. And, while it does, the moon also travels horizontally forward at the rate of 2,200 miles per hour. The two combined motions result in a curved path. The moon goes forward at just the correct speed so that our planet’s curvature drops the ground from directly beneath it at the same rate, and thus it never gets close enough to us to experience a stronger gravitational pull; that’s why it never gains speed. It travels ahead and also falls downward, maintaining the same distance, and therefore it orbits around us forever.

7. By assuming a streamlined diving position, a skydiver can attain a speed of two hundred miles per hour.

8. Galileo disproved the widespread belief that heavy objects fall faster than light ones. But when you trip and fall, shouldn’t you be pulled downward more quickly than a lighter object? The surprising answer is: you are, even though it doesn’t make you fall any faster. Heavy objects are indeed yanked more forcefully than light ones. Say you’re the late world chess champion Aron Nimzowitsch, who actually once leaped on a chess table and shouted, “Why must I lose to this idiot?” If when he jumped off he simultaneously knocked a chess piece to the floor, they both hit the ground at the same time. Gravity pulled on his body with greater power than it tugged on the pawn. However, since the chess champion weighed so much, his mass took longer to speed up, just as a truck accelerates more sluggishly than a sports car. The result is a wash. His body’s yanked with more force, but it speeds up more reluctantly, and both objects fall at the same rate.