hypercane
{{Short description|Hypothetical class of extreme tropical cyclone}}
{{Use mdy dates|date=February 2013}}
A hypercane is a hypothetical class of extreme tropical cyclone that could form if sea surface temperatures reached approximately {{convert|50|C|F|abbr=on}}, which is {{convert|12|C-change}} warmer than the warmest ocean temperature ever recorded.{{cite web |url=https://www.cbsnews.com/news/florida-ocean-temperatures-rise-to-the-90s-nearly-hitting-100/ |title=Temperature of Ocean Water |publisher=University Corporation for Atmospheric Research |work=Windows to the Universe |date=August 31, 2001 |access-date=July 24, 2008 |archive-url=https://web.archive.org/web/20120313223720/http://www.windows2universe.org/earth/Water/temp.html |archive-date=March 13, 2012 |url-status=dead }} Such an increase could be caused by a large asteroid or comet impact, a large supervolcanic eruption, a large submarine flood basalt, or "incredible" global warming.{{cite web|url=http://ipsnews.net/news.asp?idnews=30308 |title=The Dawn of the Hypercane? |first=Stephen |last=Leahy |publisher=Inter Press Service |date=September 16, 2005 |access-date=July 24, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080517014607/http://www.ipsnews.net/news.asp?idnews=30308 |archive-date=May 17, 2008 |df=mdy-all }} There is some speculation that a series of hypercanes resulting from the impact of a large asteroid or comet contributed to the demise of the non-avian dinosaurs. The hypothesis was created by Kerry Emanuel of MIT, who also coined the term.{{cite magazine |title=Did storms land the dinosaurs in hot water? |first=Jeff |last=Hecht |magazine=New Scientist |date=February 4, 1995 |url=https://www.newscientist.com/article/mg14519632.600-did-storms-land-the-dinosaurs-in-hot-water.html |issue=1963 |page=16 |access-date=July 24, 2008 }}{{cite web |url=http://wind.mit.edu/~emanuel/holem/holem.html |title=Limits on Hurricane Intensity |first=Kerry |last=Emanuel |publisher=Center for Meteorology and Physical Oceanography, MIT |date=September 16, 1996 |access-date=July 24, 2008 }}{{cite journal |title=Hypercanes: A Possible Link to Global Extinction Scenarios |first1=Kerry |last1=Emanuel |first2=Kevin |last2=Speer |first3=Richard |last3=Rotunno |first4=Ramesh |last4=Srivastava |first5=Mario |last5=Molina |journal=Journal of Geophysical Research |date=July 20, 1995 |volume=100 |issue=D7 |pages=13755–13765 |url=http://www.agu.org/pubs/crossref/1995/95JD01368.shtml |access-date=July 24, 2008 |doi=10.1029/95JD01368 |bibcode=1995JGR...10013755E |archive-date=October 2, 2012 |archive-url=https://web.archive.org/web/20121002130018/http://www.agu.org/pubs/crossref/1995/95JD01368.shtml |url-status=dead }}
Description
File:Typhoonsizes.svg, Cyclone Tracy, and the Contiguous United States. While hypercanes can be smaller than Cyclone Tracy, the largest hypercanes could even exceed Typhoon Tip in size.]]
In order to form a hypercane, according to Emanuel's hypothetical model, the ocean temperature would have to be at least {{convert|49|°C}}. A critical difference between a hypercane and present-day hurricanes is that a hypercane would extend into the upper stratosphere, whereas present-day hurricanes extend into only the lower stratosphere.{{cite interview |first=Kerry |last=Emanuel |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}{{full citation needed|date=September 2024}}
Hypercanes would have wind speeds of over {{convert|500|mph|order=flip}}, potentially gusting to {{cvt|600|mph|order=flip}},{{cite news|url=https://www.sun-sentinel.com/news/fl-xpm-1997-09-10-9709090543-story.html|title='HYPERCANE' THEORY PACKS 600 MPH WINDS|author=Michael Cabbage|newspaper=South Florida Sun Sentinel|date=10 September 1997|access-date=13 May 2019|archive-url=https://web.archive.org/web/20190513113612/https://www.sun-sentinel.com/news/fl-xpm-1997-09-10-9709090543-story.html|archive-date=May 13, 2019}} and would also have a central pressure of less than {{convert|700|hPa|inHg|2|lk=on}}, giving them an enormous lifespan of at least several weeks. The pressure drop, compared to mean sea level pressure, would be the equivalent of being at almost {{convert|3,000|m}} in elevation,{{cite web | title=Altitude to Pressure Conversion Table | website=SensorsONE | date=2024-05-22 | url=https://www.sensorsone.com/altitude-pressure-units-conversion/ | access-date=2024-05-23}} a level sufficient to cause altitude sickness.{{cite web | title=Travel to High Altitudes | website=CDC | date=2020-09-14 | url=https://wwwnc.cdc.gov/travel/page/travel-to-high-altitudes | access-date=2024-05-24}} This extreme low pressure could also support massive storm systems roughly the size of North America.{{cite web|url=https://roaring.earth/hypercane/|title=Could a 500 Mph "Hypercane" End Life As We Know It?|author=Jhaneel Lockhart|publisher=Roaring Earth|date=2017|access-date=13 March 2021}} For comparison, the largest and most intense storm on record was 1979's Typhoon Tip, with a 1-minute sustained wind speed of {{cvt|305|km/h|mph|abbr=on}} and a minimum central pressure of {{cvt|870|hPa|inHg|2}}. Such a storm would be nearly eight times more powerful than Hurricane Patricia, the storm with the highest sustained wind speed recorded, which had 1-minute sustained winds of {{convert|345|km/h|abbr=on}}.{{cite interview |first=Robert |last=Henson |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}{{full citation needed|date=September 2024}} However, hypercanes may be as small as {{cvt|15|mi|order=flip|round=5}} in size, and they would lose strength quickly after venturing into colder waters.
The waters after a hypercane could remain hot enough for weeks, allowing more hypercanes to form. A hypercane's clouds would reach {{convert|30|to|40|km|mi|round=5|abbr=on}} into the stratosphere. Such an intense storm would also damage the Earth's ozone layer, potentially having devastating consequences for life on Earth.{{Failed verification|date=May 2019}} Water molecules in the stratosphere would react with ozone to accelerate decay into O2 and reduce absorption of ultraviolet light.{{Cite web|url=https://www.lenntech.com/library/ozone/decomposition/ozone-decomposition.htm|title=ozone decomposition|website=www.lenntech.com|access-date=2019-02-05}}
Mechanism
A hurricane can be idealized as a Carnot heat engine powered by the temperature difference between the sea and the uppermost layer of the troposphere. As air is drawn in towards the eye it acquires latent heat from evaporating sea-water, which is then released as sensible heat during the rise inside the eyewall and radiated away at the top of the storm system. The energy input is balanced by energy dissipation in a turbulent boundary layer close to the surface, which leads to an energy balance equilibrium. {{citation needed|date=January 2014}}
In Emanuel's model, if the temperature difference between the sea and the top of the troposphere is too large, there is no solution to the equilibrium equation. As more air is drawn in, the released heat reduces the central pressure further, drawing in more heat in a runaway positive feedback. The actual limit to hypercane intensity depends on other energy dissipation factors that are uncertain: whether inflow ceases to be isothermal, whether shock waves would form in the outflow around the eye, or whether turbulent breakdown of the vortex happens.{{cite journal |last1=Emanuel |first1=Kerry A. |title=The Maximum Intensity of Hurricanes |journal=Journal of the Atmospheric Sciences |date=1988 |volume=45 |issue=7 |pages=1143–1155 |doi=10.1175/1520-0469(1988)045<1143:TMIOH>2.0.CO;2|bibcode=1988JAtS...45.1143E |doi-access=free }}
See also
{{Portal|Climate change|Tropical cyclones}}
References
{{Reflist}}
{{doomsday}}
{{Cyclones}}
External links
- [https://www.youtube.com/watch?v=OKqVRgZLyoM Hypercanes: The Next Big Disaster Movie?] – YouTube