The Science Behind Sandy – Why Superstorm Sandy Is Such a Super Storm

Superstorm Sandy has devastated the Eastern Seaboard. It is one of the largest hurricanes to hit the United States. It is also a freak of nature so to speak. How did Superstorm Sandy develop into the devastating storm? Many factors played parts into creating this massive, killer storm.

Satellite image of Superstorm Sandy taken at 10:00 am EDT Tuesday, Oct. 30, 2012. Image NASA GSFC

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 80o Fahrenheit 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 center 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.

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. Hurricane Sandy was a Category 1 hurricane with wind speeds up to 75 mph (150 kph).

4. 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.

5. 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.

6. Summer and winter weather are combined into one huge superstorm.

7. Sandy is a very-slow moving storm. Many locations suffered for two days or more instead of just a few hours.
8. 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.
9. 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.
10. This Superstorm hit the northeast and New York City. Subway tunnels are lower than the Hudson and many flooded.
11. Sandy had the lowest pressure of any storm  (27.76 inches) that made landfall north of Cape Hatteras. This includes the 1938 New England Hurricane with 27.96 inches. 1954’s Hazel, which had lower pressure at 27.67 inches, made landfall south of Cape Hatteras. Incidentally, the average atmosphere pressure is 29.92 inches.
12. Some experts believe Superstorm Sandy wasn’t a freak of nature, but a preview at what’s to come. “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.

 

More Information: 

Article written with help from NPR.org, News.Yahoo, Ready.Gov, CNN, Accuweather.com

 

 

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