[Dean's World] Aziz P: Category SIX hurricanes?

[notify at powerblogs.com]

Posted by Aziz P:
Category SIX hurricanes?
http://www.deanesmay.com/posts/1148389547.shtml


   All signs point to a hurricane season just as bad, if not worse, as
   last year. To add insult to injury, looks like there might well be a
   new category introduced: [1]Category 6.

     there have already been hurricanes strong enough to qualify as
     Category 6s. They'd define those as having sustained winds over 175
     or 180 mph. A couple told me they'd measured close to 200 mph on a
     few occasions.

     The Saffir-Simpson hurricane category scale is based on wind speed:
     A Category 1 hurricane has sustained winds from 74 to 95 mph,
     Category 2 has sustained winds from 96 to 110 mph, Category 3 has
     sustained winds from 111 to 130 mph, Category 4 has sustained winds
     from 131 to 155, and a Category 5 storm has sustained winds greater
     than 155 mph.

     The categories run in roughly 20 mph increments, so a Cat 6 would
     be greater than 175 or 180 mph.

     "Remember, for each 10 mph increase of wind speed," says atmosphere
     scientist Greg Holland, "there's about 10 times more damage, and 20
     times more financial loss."

     In other words, the increase is not "linear" but "exponential."

   The article points out that there is alink between gloal warming and
   hurricane strength, but overstates it slightly. As the [2]RealClimate
   folks pointed out, it's impossible to ascribe cause for any single
   event (ie, Katrina) to global warming. However, there definitely is a
   relationship - in a nutshell,

     while we cannot draw firm conclusions about one single hurricane,
     we can draw some conclusions about hurricanes more generally. In
     particular, the available scientific evidence indicates that it is
     likely that global warming will make - and possibly already is
     making - those hurricanes that form more destructive than they
     otherwise would have been.

     The key connection is that between sea surface temperatures (we
     abbreviate this as SST) and the power of hurricanes. Without going
     into technical details about the dynamics and thermodynamics
     involved in tropical storms and hurricanes (an excellent discussion
     of this can be found [3]here), the basic connection between the two
     is actually fairly simple: warm water, and the instability in the
     lower atmosphere that is created by it, is the energy source of
     hurricanes.

   The RealClimate folks also point out that Al Gore's global warming
   movie An Inconvenient Truth treated the topic of hurricanes and global
   warming with [4]the proper restraint.

   Living in Houston as I do, I evacuated last year for Rita. I
   [5]blogged the entire ordeal (scroll to the bottom and then go
   upwards). I'll be doing the same this year should the need
   unfortunately arise.

References

   1. http://abcnews.go.com/US/Science/story?id=1986862&page=1
   2. http://www.realclimate.org/index.php/archives/2005/09/hurricanes-and-global-warming/
   3. http://www.aoml.noaa.gov/hrd/hrd_sub/dynamics.html
   4. http://www.realclimate.org/index.php/archives/2006/05/al-gores-movie/
   5. http://cityofbrass.blogspot.com/2005_09_01_cityofbrass_archive.html