name of these cyclone clouds?

[DanieleItalyRm]

Hi Guys,
1 How you call these structures "rays" that are formed, often, around tropical cyclones?
2 What do these suggest?
3 Because they have this form-ray?
4 Are cirrus canopy? typical sign of outflow ?
5 These may indicate a system with a warm core?
6 Around a big thunderstorm complex can 'be a sign of a tropical system in formation?

Many Thanks,
Daniele - Italy









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[brunota2003]

What you are seeing is the cirrus canopy fanning away from the system, and they can be used as an indicator of how well the outflow channels are working with the storm. The better venting a storm gets, the more likely it is to either maintain its strength or strengthen. Not the best answer in the world, but

[DESTRUCTION5]

Those are its time to put up the shutters clouds.

(See Disclosure)

[Hurricane_Luis]

They are cirrus clouds from the outflow of the storm. As warm air rises in the eye it spreads out over the top of the storm. And as Bruno said they indicate how well the outflow channels are working within the storm.

In this image what your looking at is labelled the Cirrus Outflow Sheild.

[StarmanHDB]

As previously stated, those are very high altitude cirrus clouds which are the result of warm/moist air rising from the core/eye of a strong tropical cyclone. Once the warm air is literally sucked up to those altitudes, it flows outward in a reverse direction from the core resulting in the formation of those icy cirrus clouds.

Think of such a storm as a breathing entity - "inhaling" warm air and "exhaling" it into the high reaches of the upper atmosphere where it becomes very cold air. Furthermore, as breathing is an indicator of health, outflow indicates a very healthy, vigorous, strengthening storm.

Although I've yet to be in a hurricane since moving to South Florida, close to sunset during the approach of Tropical Storm Fay (2008), I can definitely say that strong outflow colors the sky the most eerie red I have ever seen.

[hurricanes1234]

Typhoon Nari in WPAC is displaying this phenomenon right now. Notice too, how deep the convection is. As all the previous posters said, this indicates a healthy system going through minimal wind shear, therefore, improving the outflow. However, I've seen a similar phenomenon with cirrus clouds fanning out from systems, like with Leslie last year, when the storm was going through high wind shear. I think it also happens with sheared storms, but maybe someone with more experience will shed some light on this.

[beoumont]

I have always called them "spikes."

When I see that explosive outflow around a tropical system I get quite optimist for development or rapid intensification; although that optimism does sometimes get shattered as overall conditions worsen down the road.

Although the video frame below was not taken during the spiking stage of intensification, it shows the distinct curved cirrus shield of Hurricane Erin 1995 as the eye of the storm passed offshore, 105 miles NE of Miami. I shot the video from the parking lot of the NHC, on the FIU campus in west Miami. As is obvious, the deep blue tropical skies overhead are typical of the sinking air on the periphery of a well developed tropical cyclone. There was a pretty stiff hot NNW wind blowing at the time, and those suppressed fracto-cumulus clouds were whisking rapidly across the sky.

[DanieleItalyRm]

many many Thanks a lot guys, I'm happy for your answers, I would also be grateful you respond to each question in sequence.
BUT why these formations are also present in depressions and tropical storms? not only in strong hurricanes ...
although in a more 'limited ..

[beoumont]

I have seen massive spikes as some big blobs of unorganized thunderstorms have just moved off the west coast of Africa. It simply is the cloud signature or massive outflow radiating outward from and above the area of the rapidly rising air that created those thunderstorms in the first place.

The air converges at low levels, rises rapidly in the heated air above the warm ocean, then diverges outward at 40,000+ feet or so above those thunderclouds.

As far as your "why": there are other factors that have to coincide to develop a major hurricane; and those other factors are not always present.

[AJC3]

The radial "spikes" oriented normal (90 degrees) to the anticyclonic wind flow aloft are referred to as "transverse (cirrus) bands". They occur because of the strong horizontal divergence of the intense outflow winds at the top of the TC. They are also seen quite often in mesoscale convective systems (MCS), and in (linear) strong upper level jet streaks.

I would google "transverse bands" or "transverse cirrus bands" to get more information.

Here are some good reads...

http://www.atmos.ucla.edu/~fovell/paper ... r_etal.pdf
http://journals.ametsoc.org/doi/pdf/10. ... F2222285.1
http://nldr.library.ucar.edu/repository ... 00-186.pdf
http://cimss.ssec.wisc.edu/goes/misc/980721.html
http://www.eumetsat.int/website/home/Im ... _09_A.html

[DanieleItalyRm]

Many thanks guys, I have been very useful, All of you,
So, these ray bands around these Mediterranean storms are the same thing, right?
cirrus from outflow ?

[hurricanes1234]

many many Thanks a lot guys, I'm happy for your answers, I would also be grateful you respond to each question in sequence.
BUT why these formations are also present in depressions and tropical storms? not only in strong hurricanes ...
although in a more 'limited ..

The bottom two pictures display exactly what I was talking about regarding sheared storms. The bottom right picture, Leslie, was going through heavy shear at the time of the picture, yet it still displayed that feature. I'm not sure if it's the same thing, but most probably it is. And to answer your last question, yes, those are the same phenomena in Mediterranean systems. Mediterranean systems are similar to fully-fledged tropical cyclones, except that they occur over much colder water. So they do share similar tendencies and appearances.

[DanieleItalyRm]

Many Thanks hurricanes1234,
In mediterranean not always they are formed on colder water.
the two images above:
October 2006 system occured over +25°C Sea surface
December 2005 system (like a hurricane) occurd over +20 -22°C sea surface (like Karl 1980, Vince 2005, Grace 2009, Chris 2012)
September 2003 system occurd over +26 -27°C sea surface (one of the last examples that I put to top page).