Weather Break -- Cyclone Ivan

The following is a transcript of the Weather Break radio show for Wednesday, March 12, 2008. This episode was written by Dr. Jon Schrage.

On yesterday's episode of WB, we talked about Cyclone Emma, a strong midlatitude cyclone that moved across Central Europe last week. Winds of up to 136 MPH were reported with the storm. Emma was unusually strong, but fundamentally it was cyclone just like the ones that influence the weather of NE and SD every few days.

Somewhat confusingly, another “cyclone” has been in the news lately, and that's Cyclone Ivan. Cyclone Ivan was a hurricane in the southern Indian Ocean. Ivan made landfall on the island of Madagascar on February 17, 2008. Shortly before landfall, Ivan was a category 4 hurricane, with winds of up to 135 MPH. The storm weakened slightly as it came ashore, but it was still as strong or stronger than Hurricane Katrina was when that storm hit New Orleans. Over 80 people died in Cyclone Ivan, and nearly 200,000 people were left homeless. Almost a million acres of crops were destroyed.

Normally, we don't hear much about hurricanes at this time of year. Hurricanes primarily occur in the autumn, so in the US we tend to be more aware of hurricanes in August and September. There are several reasons why autumn is the preferred time of year for hurricane formation or, technically, “tropical cyclogenesis”, but the main reason is the warm sea surface temperatures that are common at that time of year. Hurricanes get their energy from the ocean, so the time of the year with the warmest waters will generally be the time of year with the most hurricanes. Right now, the waters of the Atlantic are just too cold to support a hurricane, and no Atlantic hurricane has ever formed in the month of March. Well, no NORTH Atlantic hurricane, anyway—later this month we'll mark the anniversary of a SOUTH Atlantic hurricane, but that's a story for another day.

It's easy to forget that while March is late winter or early spring in the US, it's late summer or early fall in the Southern Hemisphere, which, of course, is where Madagascar is. Therefore, this is the time of year when islands like Madagascar or Australia would EXPECT hurricanes. The Southern Indian Ocean has seen 17 named tropical storms since November, so that is a busy part of the world for extreme weather.

Hurricanes in the Southern Hemisphere work pretty much the same way as hurricanes in the Northern Hemisphere—they are also areas of low pressure of tropical origin, they also have a ring of strong thunderstorms surroundings an “eye” of relatively undisturbed weather, and they also have their strongest winds at the surface. The main difference is the way that the winds blow—in the Northern Hemisphere, winds around a hurricane rotate counterclockwise at the surface, whereas in the Southern Hemisphere the winds rotate clockwise. The reason for the difference is the reversal of the so-call Coriolis Force at the Equator. In the Northern Hemisphere, the Coriolis Force deflects all motions to the right, whereas in the Southern Hemisphere, the Coriolis Force deflects all motions to the left. You don't notice the Coriolis Force in your day to day life, but this force becomes a critical factor in atmospheric motions.

So why did they name the storm “CYCLONE Ivan” and not “HURRICANE Ivan”? Hurricanes are actually called different things in different parts of the world. For example, in the Western Pacific, hurricanes are known as “typhoons”, even though a “typhoon” is exactly the same kind of storm that we would call a “hurricane” in the Atlantic. In the same way, in the Indian Ocean, hurricanes are called “cyclones”. There have been several important “cyclones” in the Indian Ocean in the last year, including both Cyclone Sidr and Cyclone Gonu. The terminology is just a bit confusing because in the US and in Europe the term “cyclone” means something else entirely. Here, a cyclone is an area of low pressure with fronts and a trough in the jet stream. “Cyclones” in the US have very little in common with hurricanes or “cyclones” in the Indian Ocean, other than they are both low pressure systems.

PACKING

SO..for now we are just packing which means boxes are everywhere. Unfortuneately more of them are empty right now thatn full, indicating we still have a lot of work to do!! Exciting news from our friends in Columbia today about an e-vite invitation sent for a going-away party they are having for us on March 29th. Definately a fun time to look forward to and motivation for packing more things so we can hang out and have fun that weekend.

Weather Break -- Cyclone Emma

This is a transcript of the Weather Break radio show for Tuesday, March 11, 2008. The program was written by Dr. Jon Schrage.

Last week, the weather across Central Europe made headlines throughout the meteorological community. Perhaps the most significant weather was in the form of the incredibly high winds observed in Germany. Winds were reported up to 136 MPH, and over a foot of snow fell in the Eiffel mountains of Germany. Perhaps you saw the video footage of a Lufthansa airliner trying to land at the airport in Hamburg--if not, we have links to the video and the stories on our web site at weatherbreak.creighton.edu. The plane almost crashed due to strong crosswinds on the runaway and had to pull up at the last second. The strong winds drove the waters of the Atlantic towards the shores of Western Europe in the form of a "storm surge", much like we would see in America during a hurricane. As a result, sea level was about 9 feet above normal along the coast of the Netherlands.

Several of the news stories about this wind storm casually mentioned that this weather event was called "Cyclone Emma". While the storm itself was amazing, this name actually caught our attention here at Weather Break. A cyclone, of course, is just a large area of low pressure with winds that rotate counterclockwise. In the United States, we experience cyclones every few days; if the TV weatherman tells you that a "storm system" is approaching, he usually means a cyclone.

But in the United States, we don't NAME cyclones--we name hurricanes. Tropical meteorologists have been naming hurricanes for more than 50 years now, and it's a good way to keep track of these storms. Everyone remembers famous hurricanes such as Katrina or Andrew, and even if the hurricane isn't particularly strong, the names just help the meteorologists keep the storms straight, since there is often more than one hurricane going on at a given time.

But cyclones are much more common than hurricanes. While the Atlantic ocean might see 9 or 10 named hurricanes or tropical storms in a given year, there will typically be more than 100 cyclones.

So everyone here at Weather Break was surprised to find out that cyclones in Europe DO get named, although the system is not entirely official. The names for European cyclones are assigned by the Institute of Meteorology at the Free University of Berlin. This program maintains lists of names, which get assigned to the cyclones as they form or begin to impact Western Europe.

Perhaps more amazingly, they also assign names to ANTICYCLONES. Anticyclones are areas of high pressure with winds that rotate clockwise. Anticyclones are not severe at all; they are usually associated with fair skies and gentle winds.

Each year, the Free University of Berlin releases lists of about 200 names that will be assigned to cyclones and anticyclone that year. This year, the cyclones are assigned girls' names and the anticyclones are assigned boys' names; next year, the system reverses, so cyclones will get boys' names and anticyclones will get girls' names. The names are in alphabetical order, so the first four cyclones of 2008 in Europe were Anje, Birgitta, Christine, and Dagmar, while the first four anticyclones were Andreas, Bernd, Christfried, and David. They'll go through the alphabet three or four times in 2008 before reversing the roles of girls and boys for 2009.

But what REALLY astonished everyone here at Weather Break is where these names come from. The names are submitted by the public in a type of "adoption" program that the Free University of Berlin calls "Adopt-a-Vortex". For a few hundred dollars, you can have a cyclone or an anticyclone officially named after yourself or your grandchildren or whatever. This system seemed so amazing to us that we're currently setting up an interview with someone at the Free University of Berlin to tell us more about this. Hopefully, we'll have that interview on the show next week.