“Hypercane”的意思、由来-开放百科全书

A hypercane is a hypothetical class of extreme tropical cyclone that could form if ocean temperatures reached {{convert|50|C|F|abbr=on}}, which is {{convert|15|C-change}} 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 extensive global warming.^[2] There is some speculation that a series of hypercanes resulting from an impact by 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.^[3]^[4]^[5]

Description

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]

Hypercanes would have wind speeds of over {{convert|800|km/h|mph|abbr=on}}, and would also have a central pressure of less than {{convert|70|kPa|inHg|lk=on}} (700 millibars), giving them an enormous lifespan.^[4] For comparison, the second largest and most intense storm on record was 1979's Typhoon Tip, with a wind speed of {{convert|305|km/h|mph}} and central pressure of {{convert|87|kPa|inHg|lk=on}} (870 millibars). Such a storm would be nearly eight times more powerful than Hurricane Patricia, the storm with the highest wind speed recorded.^[7]

The extreme conditions needed to create a hypercane could conceivably produce a system up to the size of North America, creating storm surges of {{convert|18|m|ft|abbr=on}} and an eye nearly {{convert|300|km|mi|abbr=on}} across.{{cn|date=June 2016}} The waters could remain hot enough for weeks, allowing more hypercanes to be formed. A hypercane's clouds would reach {{convert|30|km|mi|abbr=on}} to {{convert|40|km|mi|abbr=on}} into the stratosphere. Such an intense storm would also damage the Earth's ozone.^[4] Water molecules in the stratosphere would react with ozone to accelerate decay into O₂ and reduce absorption of ultraviolet light.^[8]

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}}

However, 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.^[5]^[9]

See also

References

1. ^{{cite web |url=http://www.windows.ucar.edu/tour/link=/earth/Water/temp.html&edu=high |title=Temperature of Ocean Water |publisher=University Corporation for Atmospheric Research |work=Windows to the Universe |date=August 31, 2001 |accessdate=July 24, 2008}}
2. ^{{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 |accessdate=July 24, 2008 |deadurl=yes |archiveurl=https://web.archive.org/web/20080517014607/http://www.ipsnews.net/news.asp?idnews=30308 |archivedate=May 17, 2008 |df=mdy-all }}
3. ^{{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 |accessdate=July 24, 2008 }}
4. ^¹²{{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 |accessdate=July 24, 2008 }}
5. ^¹{{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 |accessdate=July 24, 2008 |doi=10.1029/95JD01368 |bibcode=1995JGR...10013755E }}
6. ^{{cite interview |first=Kerry |last=Emanuel |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}
7. ^{{cite interview |first=Robert |last=Henson |title=Hypercane |work=Mega Disasters |publisher=History Channel |date=2008}}
8. ^{{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}}
9. ^{{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}}