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{{Short description|Hypothetical class of extreme tropical cyclone}}
{{Short description|Hypothetical class of extreme tropical cyclone}}
{{Use mdy dates|date=February 2013}}
{{Use mdy dates|date=February 2013}}
A '''hypercane''' is a hypothetical class of extreme [[tropical cyclone]] that could form if [[sea surface temperature]]s reached approximately {{convert|50|C|F|abbr=on}}, which is {{convert|12|C-change}} warmer than the warmest ocean temperature ever recorded.<ref>{{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 }}</ref> Such an increase could be caused by a large [[asteroid]] or [[comet]] impact, a large [[supervolcano|supervolcanic]] eruption, or a large submarine [[flood basalt]], or "incredible" [[global warming]].<ref>{{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 }}</ref> There is some speculation that a series of hypercanes resulting from the [[Impact event|impact]] of a large [[Chicxulub impactor|asteroid or comet]] contributed to the [[Cretaceous–Paleogene extinction event|demise]] of the non-avian [[dinosaur]]s.<ref name="extinction" /> The hypothesis was created by [[Kerry Emanuel]] of [[Massachusetts Institute of Technology|MIT]], who also coined the term.<ref>{{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 }}</ref><ref name="MIT">{{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 }}</ref><ref name="extinction">{{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 }}</ref>
A '''hypercane''' is a hypothetical class of extreme [[tropical cyclone]] that could form if [[sea surface temperature]]s reached approximately {{convert|50|C|F|abbr=on}}, which is {{convert|12|C-change}} warmer than the warmest ocean temperature ever recorded.<ref>{{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 }}</ref> Such an increase could be caused by a large [[asteroid]] or [[comet]] impact, a large [[supervolcano|supervolcanic]] eruption, a large submarine [[flood basalt]], or "incredible" [[global warming]].<ref>{{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 }}</ref> There is some speculation that a series of hypercanes resulting from the [[Impact event|impact]] of a large [[Chicxulub impactor|asteroid or comet]] contributed to the [[Cretaceous–Paleogene extinction event|demise]] of the non-avian [[dinosaur]]s.<ref name="extinction" /> The hypothesis was created by [[Kerry Emanuel]] of [[Massachusetts Institute of Technology|MIT]], who also coined the term.<ref>{{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 }}</ref><ref name="MIT">{{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 }}</ref><ref name="extinction">{{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 }}</ref>


==Description==
==Description==


[[File:Typhoonsizes.jpg|thumb|The relative sizes of [[Typhoon Tip]], [[Cyclone Tracy]], and the [[Contiguous United States]]. The average hypercane would not exceed Cyclone Tracy in size, though some could exceed Typhoon Tip in size]]
[[File:Typhoonsizes.svg|thumb|The relative sizes of [[Typhoon Tip]], [[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 49&nbsp;°C (120&nbsp;°F). 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.<ref>{{cite interview |first=Kerry |last=Emanuel |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}</ref>
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.<ref>{{cite interview |first=Kerry |last=Emanuel |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}</ref>{{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}},<ref name="600 mph winds">{{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}}</ref> 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.<ref name="MIT" /> The pressure drop, compared to mean sea level pressure, would be the equivalent of being at almost 3,000 m (or about 10,000 ft) in elevation,[https://www.sensorsone.com/altitude-pressure-units-conversion/] a level sufficient to cause altitude sickness.[https://wwwnc.cdc.gov/travel/page/travel-to-high-altitudes] This extreme low pressure could also support massive storm systems roughly the size of North America.<ref name="MIT" /><ref name="end life">{{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}}</ref> 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}} 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 345&nbsp;km/h (215&nbsp;mph).<ref>{{cite interview |first=Robert |last=Henson |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}</ref> 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.<ref name="600 mph winds"/>
Hypercanes would have wind speeds of over {{convert|500|mph|order=flip}}, potentially gusting to {{cvt|600|mph|order=flip}},<ref name="600 mph winds">{{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}}</ref> 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.<ref name="MIT" /> The pressure drop, compared to mean sea level pressure, would be the equivalent of being at almost {{convert|3,000|m}} in elevation,<ref>{{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}}</ref> a level sufficient to cause altitude sickness.<ref>{{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}}</ref> This extreme low pressure could also support massive storm systems roughly the size of North America.<ref name="MIT" /><ref name="end life">{{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}}</ref> 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}}.<ref>{{cite interview |first=Robert |last=Henson |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}</ref>{{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.<ref name="600 mph winds"/>


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.<ref name="MIT" />{{Failed verification|date=May 2019}} Water molecules in the stratosphere would react with [[ozone]] to accelerate decay into O<sub>2</sub> and reduce absorption of [[ultraviolet light]].<ref>{{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}}</ref>
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.<ref name="MIT" />{{Failed verification|date=May 2019}} Water molecules in the stratosphere would react with [[ozone]] to accelerate decay into O<sub>2</sub> and reduce absorption of [[ultraviolet light]].<ref>{{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}}</ref>


==Mechanism==
==Mechanism==
A hurricane functions 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}}
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 (cyclone)|eye]], or whether turbulent breakdown of the vortex happens.<ref name="extinction" /><ref>{{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 }}</ref>
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 (cyclone)|eye]], or whether turbulent breakdown of the vortex happens.<ref name="extinction" /><ref>{{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 }}</ref>

Latest revision as of 17:11, 13 October 2024

A hypercane is a hypothetical class of extreme tropical cyclone that could form if sea surface temperatures reached approximately 50 °C (122 °F), which is 12 °C (22 °F) warmer than the warmest ocean temperature ever recorded.[1] 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.[2] 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.[3] The hypothesis was created by Kerry Emanuel of MIT, who also coined the term.[4][5][3]

Description

[edit]
The relative sizes of Typhoon Tip, 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 49 °C (120 °F). 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.[6][full citation needed]

Hypercanes would have wind speeds of over 800 kilometres per hour (500 mph), potentially gusting to 970 km/h (600 mph),[7] and would also have a central pressure of less than 700 hectopascals (20.67 inHg), giving them an enormous lifespan of at least several weeks.[5] The pressure drop, compared to mean sea level pressure, would be the equivalent of being at almost 3,000 metres (9,800 ft) in elevation,[8] a level sufficient to cause altitude sickness.[9] This extreme low pressure could also support massive storm systems roughly the size of North America.[5][10] For comparison, the largest and most intense storm on record was 1979's Typhoon Tip, with a 1-minute sustained wind speed of 305 km/h (190 mph) and a minimum central pressure of 870 hPa (25.69 inHg). 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 345 km/h (214 mph).[11][full citation needed] However, hypercanes may be as small as 25 km (15 mi) in size, and they would lose strength quickly after venturing into colder waters.[7]

The waters after a hypercane could remain hot enough for weeks, allowing more hypercanes to form. A hypercane's clouds would reach 30 to 40 km (20 to 25 mi) into the stratosphere. Such an intense storm would also damage the Earth's ozone layer, potentially having devastating consequences for life on Earth.[5][failed verification] Water molecules in the stratosphere would react with ozone to accelerate decay into O2 and reduce absorption of ultraviolet light.[12]

Mechanism

[edit]

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]

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.[3][13]

See also

[edit]

References

[edit]
  1. ^ "Temperature of Ocean Water". Windows to the Universe. University Corporation for Atmospheric Research. August 31, 2001. Archived from the original on March 13, 2012. Retrieved July 24, 2008.
  2. ^ Leahy, Stephen (September 16, 2005). "The Dawn of the Hypercane?". Inter Press Service. Archived from the original on May 17, 2008. Retrieved July 24, 2008.
  3. ^ a b c Emanuel, Kerry; Speer, Kevin; Rotunno, Richard; Srivastava, Ramesh; Molina, Mario (July 20, 1995). "Hypercanes: A Possible Link to Global Extinction Scenarios". Journal of Geophysical Research. 100 (D7): 13755–13765. Bibcode:1995JGR...10013755E. doi:10.1029/95JD01368. Archived from the original on October 2, 2012. Retrieved July 24, 2008.
  4. ^ Hecht, Jeff (February 4, 1995). "Did storms land the dinosaurs in hot water?". New Scientist. No. 1963. p. 16. Retrieved July 24, 2008.
  5. ^ a b c d Emanuel, Kerry (September 16, 1996). "Limits on Hurricane Intensity". Center for Meteorology and Physical Oceanography, MIT. Retrieved July 24, 2008.
  6. ^ Emanuel, Kerry (2008). "Hypercane". Mega Disasters (Interview). History Channel.
  7. ^ a b Michael Cabbage (September 10, 1997). "'HYPERCANE' THEORY PACKS 600 MPH WINDS". South Florida Sun Sentinel. Archived from the original on May 13, 2019. Retrieved May 13, 2019.
  8. ^ "Altitude to Pressure Conversion Table". SensorsONE. May 22, 2024. Retrieved May 23, 2024.
  9. ^ "Travel to High Altitudes". CDC. September 14, 2020. Retrieved May 24, 2024.
  10. ^ Jhaneel Lockhart (2017). "Could a 500 Mph "Hypercane" End Life As We Know It?". Roaring Earth. Retrieved March 13, 2021.
  11. ^ Henson, Robert (2008). "Hypercane". Mega Disasters (Interview). History Channel.
  12. ^ "ozone decomposition". www.lenntech.com. Retrieved February 5, 2019.
  13. ^ Emanuel, Kerry A. (1988). "The Maximum Intensity of Hurricanes". Journal of the Atmospheric Sciences. 45 (7): 1143–1155. Bibcode:1988JAtS...45.1143E. doi:10.1175/1520-0469(1988)045<1143:TMIOH>2.0.CO;2.
[edit]
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