Rajdeep Deb

Superstorm Sandy: The Science Behind

Superstorm Sandy has devastated the Eastern Seaboard. It is one of the largest hurricanes to hit the United States of America. It is also a freak of nature so to speak. There are a few infamous storms over the generations, for this generation, it's likely that Sandy will be that one that people will always be talking about.

How did Superstorm develop?

Many factors played parts into creating this massive, killer storm. Hurricanes form only in the tropics where extremely moist air and heat are concentrated over the ocean, near the equator. The water temperature must be at least 26^oC both day and night. Winds blowing across the ocean in different directions begin to push masses of warm, moist air toward each other. This event is called convergence. When the air masses collide, the air in the centre starts to rise, forming an updraft. At high altitudes, the moist air of the updraft begins to cool and water droplets form. These water droplets form clouds. Large cumulonimbus clouds begin to grow and thunderstorms develop. More thunderstorms form as more convergence and updrafts occur. If the thunderstorms do not dissipate, they may start to gather together. This formation is called a tropical disturbance. Many more thunderstorms join the disturbance.

The tropical disturbance begins to swirl and becomes a vortex of thunderstorms. Updrafts are continuously pulling more air into the disturbance. When the winds begin to blow continuously at 23 miles per hour, the storm becomes a tropical depression. The tropical depression continues to gain power and becomes a tropical storm when the wind speed becomes 40 miles per hour. At any time, the disturbance, depression, or storm can run out of hot, moist air and weaken or die out. If it continues to gain strength and reaches 74 miles per hour we call it a hurricane.

Figure: Path of Sandy (Source: Wikipedia)

Ten reason “Why Sandy Is Unusual”

1. As hurricanes travel north across colder water and move across land, they tend to weaken. Sandy did not. Sandy may actually gain strength and produce strong winds inland.
2. Sandy is one of the largest, but not strongest hurricanes to ever hit the United States. Sandy’s winds covered an area of more than 1,000 miles in diameter. Usually, hurricanes only cut areas of a few hundred miles across. Sandy devastated eastern states from West Virginia to Maine.
3. Sandy is a hybrid storm morphing from a tropical storm into a winter storm powered by temperature and pressure differences. This “Frankenstorm” is packed with cold air and snow along with wind and rain.
4. Hurricane Sandy is meeting a very cold air mass from the north. This created Superstorm Sandy – a dangerous super storm that measures nearly 2,000 miles across. The cold air will be mixed into the hurricane storm. Sandy is expected to drop more than two feet of snow in West Virginia and the northeast.
5. Sandy is a very-slow moving storm. Many locations suffered for two days or more instead of just a few hours.
6. Sandy arrived during a full moon and high tides. High tides rise about 20% higher than normal during a full moon. The high tides combined with a strong storm surge pushed tidal waters 11 feet higher than usual. The greatest potential for loss of life from a hurricane is from the storm surge. Storm surge is water pushed toward the shore by the force of winds in the storm. The surge combines with the normal tides to create a storm tide. Storm surge can severely erode beaches, cause massive flooding, and wash away roads.
7. Much of the Atlantic Coast lies less than 10 feet above mean sea level. The storm surge of 11 feet or higher caused massive flooding.
8. This Superstorm hit the northeast and New York City. Subway tunnels are lower than the Hudson and many flooded.
9. As far as storm strength, Sandy barely missed the record for low barometric pressure (27.76 inHg) that made landfall north of Cape Hatteras. This includes the 1938 New England Hurricane with 27.96 inHg. 1954′s Hazel, which had lower pressure at 27.67 inHg, made landfall south of Cape Hatteras. Incidentally, the average atmosphere pressure is 29.92 inHg.
10. Superstorm Sandy wasn’t a freak of nature, some experts believe it is a preview of what’s stored. ”It’s a foretaste of things to come,” Princeton University professor Michael Oppenheimer told CNN. “Bigger storms and higher sea levels” will pile on to create a “growing threat” in the coming decades.

The climate system is so complex that present day science in the dark about it. There is a blurry idea on how global warming will affect hurricanes and about which there is more debate than knowledge.

Superstorm Sandy makes millions of victims to remain without power, but they are not powerless to do something about climate change. Hardly, anyone is drawing the link between extreme weather and global warming. This is high time to realize through this catastrophe, that our climate has changed, and the consequences are dire. Meteorologist Dr. Jeff Masters, says, "Whenever you add more heat to the oceans, you've got more energy for destruction. Hurricanes ... pull heat out of the ocean; convert it to the kinetic energy of their winds." Sandy makes us powerless but, there is a power that cannot be taken from us. That is the power to decide, on the issue of climate change, and how we can contribute to it.