Science Friday - Hurricanes

John at Axial Tilt has been working on lab activities for high school science classes and the topic is - Hurricanes.  His post is exceptional and I'm borrowing from it liberally.  It involves this map (click for the full image)

The image is a compilation of the tracks for every hurricane that has happened across the globe between 1985 and 2005. !! Those blobs of color actually resolve out to points mapping out the position of the storms at 6 hour intervals and whose color denotes the strength of the storm at that point. (The colors map to the Safir-Simpson Hurricane Scale.)

The thing that I found so compelling was that you can really see the overall patterns of hurricane formation and movement at this scale. North of the equator, they start in the low latitudes and travel westward before most of them turn to the north and ultimately end up traveling back to the east above 30 degrees N latitude. And the storms in the southern hemisphere (called tropical cyclones instead of hurricanes, btw) mirror that behavior - traveling westward, turning south and then moving east below 30 degrees S latitude. And the complete absence of them at the equator. By all accounts, it is physically possible for a storm to cross the equator, but there are no records of one actually succeeding.

If you have any questions, please run over to his post and ask in his comments.  Not only does he understand it better than me, but he's a hell of a lot nicer.

- Rick, science nerd.

 

Comments

[a rose is a rose]

nothing in south america? odd no?

[Tim Mulcahy]

I heard about a hurricane crossing the equator and hitting Brazil last year. It was the first time in recorded history that it happened.

[John]

Tim, I think your thinking of Hurricane/Cyclone Catarina in 2004. It is the first recorded hurricane in the South Atlantic, but it formed there and died there. It didn't cross the equator to get there. It's still a truly fascinating storm. You can find out a lot more about Catarina at http://en.wikipedia.org/wiki/Cyclone_Catarina

Rose, as I just said above, there has only been one recorded hurricane in the South Atlantic and only 2 recorded tropical storms too. It's really interesting. Apparently has something to do with wind shear in the upper atmosphere but I haven't quite puzzled all that out yet.

As a general note, if you view the full-sized image, you can see Catarina down on the southeast coast of Brazil. All sad and lonely by herself. :)

[Cele]

I love weather. The map is very kewl and interesting. Living in the Pacific Northwest, I of course noticed that portion of the map, and note no hurricanes despite the fact we get 74 to 100 plus winds every winter. Several places here log winds around 160mph along the headlands several times a season. And yet the map shows none of those. So sad being the bastard sister, we get ignored a lot. And yet I still love the map.

[Sideon]

**Scorpions playing in the background**

[Hilly]

Accually Catarina isn't alone. I read there where a total of nine in recored history of south alantic hurricanes/tropical deprestions/storms.