I just watched this video of a storm ripping off a roof at a petrol station
and its described as the eye of the storm, it appears that the wind just
builds and builds and then stops almost immediately
http://www.energyradio.fm/anm/templa...106&z=5&page=3

Why does the wind drop in the centre of a Hurricane?

Why does the wind drop in the centre of a Hurricane?


At the centre of a hurricane the pressure is a minimum, so there is no
pressure *gradient*, i.e. the pressure does not vary with distance. Because
the wind is caused by the pressure gradient, there is little or no wind in the
eye of the hurricane. The pressure gradient is a maximum just outside the eye
wall, where the strongest winds are.

Tudor Hughes, Warlingham, Surrey.

"TudorHgh" wrote in message
...
Why does the wind drop in the centre of a Hurricane?


At the centre of a hurricane the pressure is a minimum, so there is
no
pressure *gradient*, i.e. the pressure does not vary with distance.
Because
the wind is caused by the pressure gradient, there is little or no wind in
the
eye of the hurricane. The pressure gradient is a maximum just outside the
eye
wall, where the strongest winds are.

Tudor Hughes, Warlingham, Surrey.

Does that mean then (showing my lack of knowledge here!) that once the eye
has passed over, instead of there being a slow increase in wind speed, it
goes from virtually nothing to the highest speed in a short time?

I imagine that's why they say that the worst is to come after the eye.

Fascinating video. I noticed that there was a "cut" between the raging
winds and the still wind.
Im not sure if it really is as instant as the video suggests.

Brendan

"TudorHgh" wrote in message
...
Why does the wind drop in the centre of a Hurricane?


At the centre of a hurricane the pressure is a minimum, so there is
no
pressure *gradient*, i.e. the pressure does not vary with distance.
Because
the wind is caused by the pressure gradient, there is little or no wind in
the
eye of the hurricane. The pressure gradient is a maximum just outside the
eye
wall, where the strongest winds are.

Tudor Hughes, Warlingham, Surrey.

I don't think that is quite true. As the eye passes over the pressure
continues to drop rapidly until the center of the eye is overhead at which
point the pressure bottoms out and begins a rapid rise. The reason the eye
is calm is that as the spiralling winds converge towards the centre, there
comes a point at which the pressure gradient force cannot "pull" the winds
in any further so the air stops converging at a certain distance from the
centre of the storm. This air now has to go somewhere so it rises in
towering cumulonimbus and thus forms the eye wall. This is how I understand
it anyway.

Adam

"Brendan DJ Murphy" wrote in message
...
Fascinating video. I noticed that there was a "cut" between the raging
winds and the still wind.
Im not sure if it really is as instant as the video suggests.
Brendan


Strange..I get the impression of a series of 'still' frames mixed with some
'video' sections.
The eye of a hurricane, which can be around 40 to 80 miles in diameter, is
an area of subsiding and warming air. I understand that the strongest winds
are associated with the eye-wall of massive CB clouds which surround the
eye. I would think the transition between the relative light winds of the
eye and the surrounding maelstrom occurs over a period of several minutes,
depending on the speed the hurricane is moving. I stand to be corrected by
experts....
John
--
York,
North Yorkshire.
(Norman Virus Protected)

"Brendan DJ Murphy" wrote in message
...
Fascinating video. I noticed that there was a "cut" between the raging
winds and the still wind.
Im not sure if it really is as instant as the video suggests.
Brendan


Strange..I get the impression of a series of 'still' frames mixed with some
'video' sections.
The eye of a hurricane, which can be around 40 to 80 miles in diameter, is
an area of subsiding and warming air. I understand that the strongest winds
are associated with the eye-wall of massive CB clouds which surround the
eye. I would think the transition between the relative light winds of the
eye and the surrounding maelstrom occurs over a period of several minutes,
depending among other things, on the speed the hurricane is moving.
Adam has given the main reason why the 'eye' exists, though the mechanics
are complex and still, I think, not fully understood.
As always...I stand to be corrected by experts....
John
--
York,
North Yorkshire.
(Norman Virus Protected)

In article , johndotwhitby12
@ntlworld.com says...
Strange..I get the impression of a series of 'still' frames mixed with some
'video' sections.

Right click. Select plug-insoptions performance tab and set the network
buffering to something like 120 seconds.




The eye of a hurricane, which can be around 40 to 80 miles in diameter, is
an area of subsiding and warming air.

40 miles? I seem to remember an eye of 8 miles somewhere and 20 miles is
quite common. Ivan had a 20 mile eyewall several times.


I understand that the strongest winds
are associated with the eye-wall of massive CB clouds which surround the
eye. I would think the transition between the relative light winds of the
eye and the surrounding maelstrom occurs over a period of several minutes,
depending on the speed the hurricane is moving. I stand to be corrected by
experts.

Pity the video cut from the actual destruction to the eyewall although I
suspect that the time difference between the two was quite large,and
thus, it was a video of the destruction of a garage rather than a video
of an eyewall.

--
Alan LeHun

I don't think that is quite true. As the eye passes over the pressure
continues to drop rapidly until the center of the eye is overhead at which
point the pressure bottoms out and begins a rapid rise. The reason the eye
is calm is that as the spiralling winds converge towards the centre, there
comes a point at which the pressure gradient force cannot "pull" the winds
in any further so the air stops converging at a certain distance from the
centre of the storm. This air now has to go somewhere so it rises in
towering cumulonimbus and thus forms the eye wall. This is how I understand
it anyway.


You're right, but I was trying to simplify it for the original
questioner.

Tudor Hughes.

"Alan LeHun" wrote in message
...
In article , johndotwhitby12
@ntlworld.com says...
Strange..I get the impression of a series of 'still' frames mixed with
some
'video' sections.

Right click. Select plug-insoptions performance tab and set the network
buffering to something like 120 seconds.




The eye of a hurricane, which can be around 40 to 80 miles in diameter,
is
an area of subsiding and warming air.

40 miles? I seem to remember an eye of 8 miles somewhere and 20 miles is
quite common. Ivan had a 20 mile eyewall several times.


I understand that the strongest winds
are associated with the eye-wall of massive CB clouds which surround the
eye. I would think the transition between the relative light winds of
the
eye and the surrounding maelstrom occurs over a period of several
minutes,
depending on the speed the hurricane is moving. I stand to be corrected
by
experts.

Pity the video cut from the actual destruction to the eyewall although I
suspect that the time difference between the two was quite large,and
thus, it was a video of the destruction of a garage rather than a video
of an eyewall.

--
Alan LeHun

Those videos show you the awesome power of these things. In that third clip
the wind at times sounded like concorde going overhead.

Adam