How to Destroy the Universe Read Online Free PDF Page B

each inward-moving current is deflected to the right. In fact, it’s a general tendency of the Coriolis effect in the northern hemisphere to make air currents veer to the right; in the south it makes them veer to the left. And this is what makes the cool air currents headingtoward the equator in the northern and southern hemispheres both veer west to create the trade winds at the equator. These winds blow cyclones in a westerly direction.
The Saffir–Simpson scale
    Scientists classify the strength of hurricanes on what is known as the Saffir–Simpson scale, first put forward by US engineer Herbert Saffir and US meteorologist Bob Simpson in 1969. The weakest hurricanes are category 1, which have windspeeds between 119–153 km/h (74–95 mph); the strongest hurricanes are category 5, with winds exceeding 250 km/h (155 mph). The center of a hurricane is a region of calm known as the “eye,” which is typically about 50 km (30 miles) across. The air pressure here is low because convection is at its strongest, sucking warm air away from sea level like a vacuum cleaner. The warm, rising air currents spiral up around the edge of the eye forming a thick bank of rapidly rotating cloud called the “eyewall.” It’s here that the strongest winds are found and rainfall is at its most torrential.
Project Stormfury
    The strength of a hurricane diminishes rapidly once it reaches land, as its energy source—the warm ocean—disappears from under it. This means that whilecoastal regions are especially prone, moving 10–20 km (6–12 miles) inland is often enough to escape the worst effects. That works for saving lives, but what about property damage? After all, there’s no way a whole city can be uprooted and moved to safer ground. Is there any way we could influence the physics underpinning a hurricane to alter its course or even stop it in its tracks? One of the earliest efforts to try to change the behavior of hurricanes was the US Project Stormfury, which began in the 1960s. This was an effort to weaken hurricanes by stimulating rainfall within them using a technique called cloud seeding. The idea is for aircraft to fly above the hurricane and drop into it chemical particles with a crystal structure resembling that of ice, such as silver iodide. This encourages water vapor in the storm to cool and condense into clouds, which then fall to the ground as rain. It was believed this would cause the eyewall in a hurricane to get bigger. Just like the spinning ice skater pulls her arms in to go faster and stretches them out to slow down, so windspeed becomes lower as the eyewall gets larger. However, the results of Project Stormfury were inconclusive and it was abandoned.
    Recently, US meteorologist Dr. Ross Hoffman has carried out computer simulations showing the effect of heating hurricanes. He found that increasing the temperature at high altitude by just 2–3°C (4–5°F) can have a major effect on a hurricane’s course. Heatingthe top of the hurricane decreases the vertical temperature gradient, weakening the convection currents that drive it. Hoffman suggests this heating might be achieved using a flotilla of satellites, which could bombard a hurricane with microwaves from above. Another proposal is to disperse soot particles in the hurricane’s upper cloud layers. Soot, or indeed anything else black, absorbs heat. Clouds of it in a hurricane’s upper decks would absorb sunlight, heating the clouds in much the same way as microwaves. Yet another option is to smother the hurricane in particles of Dyn-O-Gel, a polymer compound that can absorb as much as 1,500 times its own weight in water, soaking up the hurricane’s heat-carrying moisture and robbing it of its energy source.
Cool hurricanes
    Other scientists have proposed fighting hurricanes from the opposite direction—the ocean surface. One proposal is to lay down a slick of biodegradable oil over the