Sandy: What Makes Hurricanes so Dangerous

Storms crossing the Atlantic, set in America in damage and return as rain front.

They uproot entire forests, detached blow through the air and break them down, press Viermaster shallow sea like a toy boat in the bathtub, make up of the mouth of rivers flow into the country Hurricanes are among the most violent natural events.

Only for the residents of the “old world”, the Europeans, they are not among the Urerlebnissen whose experience would be stored in their genes. The hurricane in the North Atlantic has something exotic, like the cyclone in the Pacific and the typhoon in South and South-east Asia, the name all one and the same natural phenomenon: the tropical cyclone.

Since 1953, hurricanes bear names – initially only female, alternately from 1979 boys and girls names. That made it easy to contemporaries in this country, some of the most momentous hurricanes lashed firmly to the memory.

Ever since the 90s, as the spoken off-screen TV weather in skits from “Wettertainern” changed and we must follow as the track of the large, menacing swirl regularly in real time and marvel at, from their origin near the Cape Verde islands over in the Caribbean and the U.S. East Coast. “Hugo” in the 80’s is one of them, “Andrew” in the 90s and especially “Katrina,” that tragic disaster, which in 2005 devastated in and around New Orleans around the U.S. states of Louisiana and Mississippi, a total of approximately 2250 deaths demanded.

Increasingly, more and more violent?

15 years ago was added as yet another factor in the observation of hurricanes, many researchers believe that the storms are now more frequent and more violent plague the east coast of America, because man heats the Earth.So we take the blame for the hurricane? A still hotly contested issue.

“Sandy,” the hurricane, which is expected to reach in the night from Monday to Tuesday somewhere between Washington and New York, the mainland could, possibly, even among the better-known hurricanes, even if it should not flood the subways of Manhattan.

“Sandy” is with 1500 kilometers in diameter (a half times the U.S. state Texas) the second largest hurricane, any rate since 30 years, began than satellites, to measure this. Only “Olga” (2001) was during this time with 2000 kilometers even bigger .

A comparatively later Hurricane

But above all, “Sandy” is a comparatively later hurricane, and he has widely succeeded in the north up the Atlantic coast – a combination that is him just before the critical landfall brought an explosive encounter, even a violent “tuning” means ” baroklinische “gain in terms of what it meteorologists.

It “Sandy” meets namely now already very icy and upstanding air masses that come against from Canada. If they fall down and even in the south heated, warm air in the opposite direction in the vortex rises, receives this energy inherent in a hefty boost.

The wind speed at its most vibrant areas will increase. And hence the force with which the hurricane. The waves coming from the otherwise phlegmatic Sargasso Sea, outside in the Bermudas, zoom whipped to the coasts of Maryland, according to Delaware, New Jersey and New York might just as well

Up to ten meters high on, upset additionally through the shallow waters, are to the waves zoom rustle allegedly, what would then inform the shore fronts of “Downtown” Manhattan under water.

A rather Moderatorer Monday afternoon

It included the Monday afternoon estimated around 140 km far from being one of the highest in hurricanes, more likely to be moderate. By comparison, the strongest ever recorded in a tropical cyclone speed reached 407 km / h, the cyclone “Olivia” that descended upon 1996 on the northwest coast of Australia.

Because it is very lonely there, the consequences – ten dead and two million dollars damage – indeed tragic, but relatively small. Even the hurricanes “Vivian” and “Wiebke” both swept over Germany in 1990, came to each peak of 285 kilometers per hour.

And we remember still to the Orkan “Andrea” adopted last January via Western and Central Europe, the it also still brought on 270 “Sachen”? The dangers are now feared by “Sandy” are, according to estimates by meteorologists and authorities as well as not in the wind. Hazardous were potential flooding that may occur as a result of the winds on a very broad front on the coast.

No more, but devastating

Has increased the risk of hurricanes, they occur more frequently in recent years, they are always strong, they always focus on more damage? The questions appeared in connection with the debate on climate change.

Hurricanes arising exclusively in the oceans (except for the rare phenomenon of “Medicane” Mediterranean) need to “spark” a sea surface temperature of at least 26.5 degrees. What could be more than the assumption that they are piling up, if in the course of global warming, the oceans heat up? Therefore oceanographer went first also assume.

It is now known, however, that the increase in water temperature not only provides energy for emerging hurricanes, but also for wind shear to ensure that the newborn vortex destroy once again. The reading of the IPCC is because even today: No more hurricanes, but more powerful, more devastating coming to us.

Context to explain difficult

This statement, however, is determined by the hurricane history hardly supported by either the long term or year by looking at the past ten years.

Several factors make clear statements about this connection: First, the sea temperature rose in the past decades to by no means straightforward, just put in the last few years rather take a break.

For the second subject, the number and the intensity of hurricanes (as well as the hurricanes of the other hemispheres) long-term variations in the rhythm of 30, 40 or even more years.

Third, there is little reliable data on the number, size and speed of hurricanes at sea from previous years. Only the satellite observation provided for the past 30 years a reliable basis. What lies further back, can only be based on random observations on logbooks and other records of seafarers.

Accurate history in wars

After all, can be a significant proportion of hurricanes traced back many years: those hurricanes that hit the American coast. Most accurately the history is mostly when it comes to war.

So it is now considered virtually undisputed that at least the most consequential hurricane of all time was the still unnamed “Great Hurricane” from 1780, which claimed the middle of the American Revolutionary War from 20,000 to 22,000 deaths – a number equal to the total since in no hurricane season more was reached. His strength, wind speed can only be estimated – according to contemporary reports, they should have been enormous.

A problem for the direct comparison: There was no early warning systems that would have the number of victims may press. On the other hand in the affected areas also lived only a fraction of today’s population.

Variation in the rhythm of decades

Since the year 1851 from America are record the number and strength of hurricanes that reached the United States. Christopher Landsea of the National Hurricane Center of the United States in Miami, Florida, has compiled them.

On the official website they are easy to understand.This can be either in the strength (divided into five classes) nor in the intensity see an upward trend, but a variation in the rhythm of decades. With some high points in the 1850s, the 1930s and the 1990s Marine researchers suspect here a correlation with the long-term fluctuation at the deeper currents and general weather situations, the “multidecadal oscillations”.

Most fatal hurricane in this period: the famous hurricane of 1900 devastated the city Galveston, Texas, with 8,500 to 12,000 deaths, the second heaviest misfortune.

Four hurricanes simultaneously

Sandy: What Makes Hurricanes so Dangerous 2

Among the fiercest hurricane years are certainly in 1893 and 1998, when four tropical cyclones were simultaneously (which can not be excluded for lack of accurate data collection is that it was 1893 even more).

As for the current year, are more accurate data. From 2003 to today, the number of major hurricanes especially took tends to decrease more. What has risen in recent decades, certainly, are only the values ??that are destroyed during hurricanes.

The origin of hurricanes on our side of the Atlantic coast of Africa. It was only on the other side they put to the great damage. However, we can not always assume completely unmolested.

Some moderate tornado “bounced” ultimately “down” from the American coast, is carried back by the huge, clockwise running North Atlantic roundabout. And given us, the normal depth degenerated a rain front.

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