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Add: bibcode, authors 1-1. Removed parameters. Some additions/deletions were parameter name changes. | Use this bot. Report bugs. | Suggested by Abductive | Category:Weather hazards | via #UCB_Category 24/94
Expand article and added a bibliography. Might be a little technical still, but hopefully a little less now.
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[[File:Global Hawk measures a burst of convection called a Hot Tower.ogv|thumb|upright=1.3|A NASA [[Global Hawk]] detects a hot tower measuring over {{cvt|12|km}} high within the eyewall of [[Hurricane Karl (2010)|Hurricane Karl]] on September 16, 2010.|alt=Animation of a drone scanning a hurricane]]
{{Technical|date=October 2018}}
A '''hot tower''' is a tropical [[cumulonimbus cloud]] that reaches out of the lowest layer of the atmosphere, the [[troposphere]], and into the [[stratosphere]].<ref name="DiscoveringHotTowers">{{cite web |last1=Voiland |first1=Adam |title=Discovering Hot Towers |url=https://earthobservatory.nasa.gov/blogs/earthmatters/2012/09/12/discovering-hot-towers/ |website=Earth Observatory |publisher=NASA |access-date=16 March 2021 |date=12 September 2012}}</ref> These formations are called "hot" because of the large amount of [[latent heat]] released as [[water vapor]] condenses into liquid and freezes into ice within the cloud. Hot towers in regions of sufficient [[vorticity]] may acquire rotating updrafts; these are known as ''vortical hot towers''. The role of hot towers in [[tropical meteorology|tropical weather]] was first formulated by [[Joanne Simpson]] in 1958. Hot towers dominated discussions in tropical meteorology in the 1960s and are now considered the main drivers of rising air within [[tropical cyclone]]s and a major component of the [[Hadley circulation]]. Although the prevalence of hot towers in scientific literature decreased in the 1970s, hot towers remain an active area of research. The presence of hot towers in [[tropical cyclone]]s is correlated with an increase in the tropical cyclones's intensities.<ref name="Hurricane Monster">{{cite web |last1=Chohan |first1=Rani |title=Scientists Discover Clues to What Turns a Hurricane into a Monster |url=https://www.nasa.gov/vision/earth/environment/Hot_Towers.html |publisher=NASA |access-date=16 March 2021 |location=12 January 2004}}</ref>
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[[File:Global Hawk measures a burst of convection called a Hot Tower.ogv|thumb|350px|A NASA [[Global Hawk]] detects a hot tower measuring over 12 kilometers high within the eyewall of [[Hurricane Karl (2010)|Hurricane Karl]] on September 16, 2010.]][[Image:Hottower.jpg|thumb|250px|Hot tower in 1998's [[Hurricane Bonnie (1998)|Hurricane Bonnie]]. Altitudes of clouds are exaggerated.]]


== Observation ==
A '''hot tower''' is a tropical [[cumulonimbus]] cloud that reaches out of the lowest layer of the atmosphere, the [[troposphere]], and into the [[stratosphere]]. In the tropics, the border between the troposphere and stratosphere, the [[tropopause]], typically lies at least {{convert|15|km|mi}} above [[sea level]]. These formations are called "hot" because of the large amount of [[latent heat]] released as water vapor condenses into liquid and freezes into ice.<ref name="nasa2">{{cite web|url=http://www.nasa.gov/vision/earth/environment/Hot_Towers.html|title=Scientists Discover Clues to What Turns a Hurricane into a Monster|last=Chohan|first=Rani|date=2004-01-12|access-date=2009-01-07}}</ref> The presence of hot towers within the [[Eye (cyclone)|eyewall]] of a [[tropical cyclone]] can indicate possible future strengthening.<ref>{{Cite journal|last1=Zhuge|first1=Xiao-Yong|last2=Ming|first2=Jie|last3=Wang|first3=Yuan|date=2015-10-01|title=Reassessing the Use of Inner-Core Hot Towers to Predict Tropical Cyclone Rapid Intensification|url=https://journals.ametsoc.org/view/journals/wefo/30/5/waf-d-15-0024_1.xml|journal=Weather and Forecasting|language=EN|volume=30|issue=5|pages=1265–1279|doi=10.1175/WAF-D-15-0024.1|bibcode=2015WtFor..30.1265Z|issn=1520-0434|doi-access=free}}</ref>
Hot towers were first detected by [[weather radar|radar]] in the 1950s.<ref name="DiscoveringHotTowers" /> Aerial reconnaissance was used to probe hot towers, though planes avoided the most dangerous cores of hot towers due to safety concerns.{{sfn|Fierro et al. (2009)|p=2731}} The launch of the [[Tropical Rainfall Measuring Mission]] (TRMM) in 1997 provided the resolution and coverage necessary to systematically catalog hot towers and precisely assess their structure globally.<ref name="DiscoveringHotTowers" /> Prior to 1997, the small size and short duration of hot towers limited studies of hot towers to aerial observations as the resolutions of satellite sensors at [[microwave]] and [[infrared]] wavelengths were to coarse to properly resolve details within hot towers.<ref name="Katrina Hot Towers">{{cite web |last1=Perkins |first1=Lori |title=Hurricane Katrina Hot Towers |url=https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3253 |website=Scientific Visualization Studio |publisher=NASA |access-date=16 March 2021 |date=15 September 2005}}</ref>


==Origin of term==
== Structure ==
The term ''hot tower'' has been applied to both rapidly rising parcels of air and the tall [[cumulonimbus cloud]]s that accompany them.<ref name="DiscoveringHotTowers" />{{sfn|Guimond et al. (2010)|p=634}} The regions of rising air are horizontally small and span about {{cvt|2|–|4|km}} across.{{sfn|Guimond et al. (2010)|p=634}}{{sfn|Fierro et al. (2009)|p=2731}} Their greatest extent is in the vertical, reaching altitudes as high as {{cvt|18|km}} and exhibiting high [[reflectivity]].{{sfn|Heymsfield et al. (2010)|p=286}} Hot towers are effectively undilute; as they ascend, the surrounding air does not mix with the rising parcels of air.{{sfn|Montgomery et al. (2006)|p=356}}{{sfn|Anthes (2003)|p=144}} As a result, the [[equivalent potential temperature]] within a hot tower remains nearly constant throughout their entire vertical extent. This allows for efficient transport of heat from the lower [[troposphere]] to the [[stratosphere]]. Hot towers forming within areas of rotation may feature rotating [[updraft]]s; these are known as ''vortical hot towers'' and are associated with localized regions of anomalous vertical [[vorticity]].{{sfn|Anthes (2003)|p=144}}
The hot tower hypothesis was proposed in 1958 by [[Herbert Riehl]] and [[Joanne Simpson]] after extensive study of [[moist static energy]] profiles in the tropics.<ref name=simpson>{{cite web|url=http://earthobservatory.nasa.gov/Features/Simpson/simpson3.php|title="Hot Tower" Hypothesis|publisher=[[NASA Earth Observatory]]|access-date=2008-08-28}}</ref> Prior to 1958, the mechanism driving atmospheric [[Hadley cell]]s was poorly understood. Riehl and Simpson proposed that the energy feeding these [[convection|convective]] cells was supplied by the release of [[latent heat]] during condensation and subsequent freezing of warm, moist air in areas of convection about {{convert|5|km|mi}} wide. The large horizontal extent of these convective cells provides a buffer from the dry air surrounding the convective region that allows the parcel to rise at nearly the moist adiabatic [[lapse rate]].{{Clarify|reason=Too technical|date=October 2018}} [[NOAA]] also defined the term ''Towering cumulonimbus'' in 2009.<ref>[http://www.srh.noaa.gov/oun/?n=spotterglossary4 Towering cumulonimbus]</ref>


== Conceptual development ==
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==Effects on tropical cyclones==
[[File:DaisyAug2819580530UTCNavyRecon.png|thumb|left|Aerial studies of Hurricane Daisy in 1958 were pivotal in validating the relationship between hot towers and tropical cyclones]]
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In 2007, the [[National Aeronautics and Space Administration]] (NASA) hypothesized that the [[wind shear]] between the eye and the eyewall could enhance updraft through the center of a cyclone and generate convection.<ref>{{cite web|author=National Aeronautics and Space Administration|url=http://svs.gsfc.nasa.gov/vis/a000000/a003400/a003413/index.html|title=Hot towers simulation|year=2007|publisher=NOAA|access-date=2009-09-18}}</ref> Hot towers may appear when a cyclone is about to intensify, possibly [[Rapid intensification|rapidly]]. A particularly tall hot tower rose above [[Hurricane Bonnie (1998)|Hurricane Bonnie]] in August 1998, as the storm intensified before striking [[North Carolina]].<ref name="NCDC">{{cite web|author=National Climatic Data Center|url=http://lwf.ncdc.noaa.gov/oa/reports/bonnie/bonnie.html#INTRO|title=Bonnie Buffets North Carolina!|year=1998|publisher=NOAA|access-date=2009-01-07|url-status=dead|archive-url=https://web.archive.org/web/20080916091724/http://lwf.ncdc.noaa.gov/oa/reports/bonnie/bonnie.html#INTRO|archive-date=2008-09-16}}</ref>
Before the 1950s, the mechanism driving atmospheric [[Hadley cell]]s—an air circulation that transports tropical heat and moisture poleward—was poorly understood.<ref name="Hot Tower Hypothesis" /> It was initially believed that the Hadley cell was fueled by the broad, diffuse, and gradual rise of warm and moist air near the equator. However calculations of [[Earth's energy budget]] using data from [[World War II]] showed that the mid-troposphere was an energy deficit region, indicating that the maintenance of the Hadley cell could not be explained by the broad ascent of air.{{sfn|Fierro et al. (2009)|p=2731}} The role of the tropical regions in the global climate system and the development of tropical disturbances were also poorly understood. The 1950s marked a pivotal decade that saw the advancement of [[tropical meteorology]], including the creation of the U.S. [[National Hurricane Research Project]] in 1956.{{sfn|Anthes (2003)|p=139}} In 1958, [[Herbert Riehl]] and [[Joanne Simpson]] proposed that the release of latent heat caused by condensation within hot towers supplied the energy necessary to maintain Hadley cells and the [[trade winds]]; their hypothesis was initially based on aerial observations made by Simpson during her time at [[Woods Hole Oceanographic Institution]].<ref name="Hot Tower Hypothesis" /> This mechanism required the existence of undilute cumulonimbus clouds that did not [[entrainment (meteorology)|entrain]] the surrounding air, allowing for the efficient transfer of heat from the ocean surface into the upper troposphere.{{sfn|Anthes (2003)|p=140}} The existence of 1,500–2,500 of these clouds was required if they were to support the Hadley circulation.{{sfn|Fierro et al. (2009)|p=2731}} The resarchers also argued that hot towers helped maintain the warmth present at the center of [[tropical cyclone]]s and that the ascent of moist air within tropical cyclones was concentrated around the hot towers.<ref name="Warm Core Mystery">{{cite book|last1=Weier|first1=John|title=Joanne Simpson (1923–2010) |chapter=Warm Core Mystery |chapter-url=https://earthobservatory.nasa.gov/features/Simpson/simpson4.php|url=https://earthobservatory.nasa.gov/features/Simpson |website=Earth Observatory |publisher=NASA |access-date=16 March 2021 |date=April 28, 2004}}</ref> In their original 1958&nbsp;paper outlining the role of hot towers, Riehl and Simpson described these clouds as "narrow warm towers", but began terming the idea as the "hot tower hypothesis" by 1960.{{sfn|Anthes (2003)|p=140}}<ref name="Hot Tower Hypothesis">{{cite book|last1=Weier|first1=John|title=Joanne Simpson (1923–2010) |chapter=“Hot Tower” Hypothesis |chapter-url=https://earthobservatory.nasa.gov/features/Simpson/simpson3.php|url=https://earthobservatory.nasa.gov/features/Simpson |website=Earth Observatory |publisher=NASA |access-date=16 March 2021 |date=April 28, 2004}}</ref> For the next two decades, hot towers dominated scientific discussion concerning the interaction between [[cumulus cloud]]s and their larger-scale tropical environments.{{sfn|Anthes (2003)|p=139}}


[[File:Hottower.jpg|thumb|right|Visualization of a hot tower in [[Hurricane Bonnie (1998)]]. Cloud heights are exaggerated.|alt=Visualization of moisture concentrations in a hurricane]]
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==See also==
Aerial observations of [[Hurricane Daisy (1958)|Hurricane Daisy]] in [[1958 Atlantic hurricane season|1958]] suggested that [[atmospheric convection|convection]] within tropical cyclones was limited to a few areas of cumulonimbus clouds, dispelling the idea that rising air was distributed throughout the entire cyclone's envelope and lending support for the hot tower hypothesis.{{sfn|Anthes (2003)|p=140}} In the case of Hurricane Daisy, the convecting cumulonimbus clouds represented only about four percent of the total region of [[precipitation]] associated with the hurricane. A 1961 analysis by Riehl and Simpson using the NHRP data from Hurricane Daisy concluded that hot towers were the principal mechanism by which tropical cyclones move warm air into the upper troposphere. The newfound importance of hot towers in tropical cyclones motivated the development of [[parametrization (atmospheric modeling)|parametrization]]—the representation of small-scale phenomena and interactions, i.e. individual cumulus clouds—in early [[numerical weather prediction|weather models]].{{sfn|Anthes (2003)|p=141}} The hot tower hypothesis also inspired the development of [[convective instability|convective instability of the second kind]] (CISK): a conceptual model that emphasized the [[positive feedback|feedback]]s between the latent heat released by individual cumuli and the convergence associated with tropical cyclones.{{sfn|Anthes (2003)|p=143}} By the 1970s, many of the ideas and predictions put forth by the hot tower hypothesis had been validated by empirical observations.{{sfn|Anthes (2003)|p=144}} Critics of the hot tower hypothesis contended it was implausible that a cumulonimbus cloud could be free of entrainment.<ref name="Hot Tower Hypothesis" /> This facet of the hypothesis remained untested until dropsondes released into hot towers as part of the Convection and Moisture Experiment in 1998 provided the first direct measurements of the thermodynamic structure of hot towers. The data showed that the [[equivalent potential temperature]] within hot towers was virtually constant across their entire vertical extent, confirming the lack of entrainment.{{sfn|Anthes (2003)|p=144}} Other field observations have suggested that some tropical updrafts are diluted by their surrounding environments at altitudes lower than {{cvt|5|km}}, though strong latent heat generated by [[Hurricane dynamics and cloud microphysics|ice within the cloud]] was sufficient to provide the requisite input energy for the Hadley circulation.{{sfn|Fierro et al. (2009)|p=2745}} Scientific research of hot towers experienced a resurgence in the 2000s with a renewed focus on their role in [[tropical cyclogenesis]] and tropical cyclone development.{{sfn|Guimond et al. (2010)|p=634}}

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== Effect on tropical cyclones ==
Vortical hot towers aid in the formation of tropical cyclones by producing many small-scale positive anomalies of [[potential vorticity]], which eventually coalesce to strengthen the broader storm.{{sfn|Hendricks et al. (2004)|p=1209}} The high vorticity present in the hot towers traps the latent heat released by those clouds, while the merger of the hot towers aggregates this enhanced warmth.{{sfn|Hendricks et al. (2004)|p=1229}} These processes are the major part of the initial formation of a tropical cyclone's warm core—the anomalous warmth at the center of such a system—and the increased [[angular momentum]] of the winds encircling the developing cyclone.{{sfn|Hendricks et al. (2004)|p=1209}}

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In 2007, the [[National Aeronautics and Space Administration]] (NASA) hypothesized that the [[wind shear]] between the eye and the eyewall could enhance updraft through the center of a cyclone and generate convection.<ref>{{cite web|author=National Aeronautics and Space Administration|url=http://svs.gsfc.nasa.gov/vis/a000000/a003400/a003413/index.html|title=Hot towers simulation|year=2007|publisher=NOAA|access-date=2009-09-18}}</ref> Hot towers may appear when a cyclone is about to intensify, possibly [[Rapid intensification|rapidly]]. A particularly tall hot tower rose above [[Hurricane Bonnie (1998)|Hurricane Bonnie]] in August 1998, as the storm intensified before striking [[North Carolina]].<ref name="NCDC">{{cite web|author=National Climatic Data Center|url=http://lwf.ncdc.noaa.gov/oa/reports/bonnie/bonnie.html#INTRO|title=Bonnie Buffets North Carolina!|year=1998|publisher=NOAA|access-date=2009-01-07|url-status=dead|archive-url=https://web.archive.org/web/20080916091724/http://lwf.ncdc.noaa.gov/oa/reports/bonnie/bonnie.html#INTRO|archive-date=2008-09-16}}</ref>
{{clear}}
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== See also ==
{{Portal|Tropical cyclones}}
{{Portal|Tropical cyclones}}
* [[List of cloud types]]
* [[List of cloud types]]
* [[Pileus (meteorology)|Pileus]]
* [[Tropical cyclone]]
* [[Overshooting top]]
* [[Rapid intensification]]


==References==
== References ==
*{{cite journal |journal=Geophysica |last1=Riehl |first1=Herbert |last2=Malkus |first2=Joanne |volume=6 |number=3–4 |pages=503–538 |year=1958 |title=On the heat balance in the equatorial trough zone }}
*{{cite journal |title=Some Views On "Hot Towers" after 50 Years of Tropical Field Programs and Two Years of TRMM Data |first1=Edward J. |last1=Zipser |journal=Meteorological Monographs |year=2003 |volume=29 |number=51 |pages=49–58 |bibcode = 2003MetMo..29...49Z |doi = 10.1175/0065-9401(2003)029<0049:CSVOHT>2.0.CO;2 }}
{{Reflist}}
{{Reflist}}

== Bibliography ==
{{refbegin|2}}
* {{cite book |last1=Anthes |first1=Richard A. |editor1-last=Tao |editor1-first=Wei-Kuo |editor2-last=Adler |editor2-first=Robert |title=Cloud Systems, Hurricanes, and the Tropical Rainfall Measuring Mission (TRMM) |chapter=Hot Towers and Hurricanes: Early Observations, Theories, and Models |date=2003 |pages=139–148 |doi=10.1007/978-1-878220-63-9_10 |ref={{sfnRef|Anthes (2003)}} |publisher=American Meteorological Society |location=Boston, Massachusetts |via=Springer Link |isbn=978-1-878220-63-9}}
* {{cite journal |last1=Fierro |first1=Alexandre O. |last2=Simpson |first2=Joanne |last3=LeMone |first3=Margaret A. |last4=Straka |first4=Jerry M. |last5=Smull |first5=Bradley F. |title=On How Hot Towers Fuel the Hadley Cell: An Observational and Modeling Study of Line-Organized Convection in the Equatorial Trough from TOGA COARE |journal=Journal of the Atmospheric Sciences |date=September 2009 |volume=66 |issue=9 |pages=2730–2746 |doi=10.1175/2009JAS3017.1 |ref={{sfnRef|Fierro et al. (2009)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}} {{open access}}
* {{cite journal |last1=Guimond |first1=Stephen R. |last2=Heymsfield |first2=Gerald M. |last3=Turk |first3=F. Joseph |title=Multiscale Observations of Hurricane Dennis (2005): The Effects of Hot Towers on Rapid Intensification |journal=Journal of the Atmospheric Sciences |date=March 2010 |volume=67 |issue=3 |pages=633–654 |doi=10.1175/2009JAS3119.1 |publisher=American Meteorological Society |location=Boston, Massachusetts|ref={{sfnRef|Guimond et al. (2010)}}}} {{open access}}
* {{cite journal |last1=Hendricks |first1=Eric A. |last2=Montgomery |first2=Michael T. |last3=Davis |first3=Christopher A. |title=The Role of “Vortical” Hot Towers in the Formation of Tropical Cyclone Diana (1984) |journal=Journal of the Atmospheric Sciences |date=June 2004 |volume=61 |issue=11 |pages=1209–1232 |doi=10.1175/1520-0469(2004)061<1209:TROVHT>2.0.CO;2 |ref={{sfnRef|Hendricks et al. (2004)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}} {{open access}}
* {{cite journal |last1=Heymsfield |first1=Gerald M. |last2=Tian |first2=Lin |last3=Heymsfield |first3=Andrew J. |last4=Li |first4=Lihua |last5=Guimond |first5=Stephen |title=Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar |journal=Journal of the Atmospheric Sciences |date=1 February 2010 |volume=67 |issue=2 |pages=285–308 |doi=10.1175/2009JAS3132.1 |ref={{sfnRef|Heymsfield et al. (2010)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}}
* {{cite journal |last1=Houze |first1=Robert A. Jr. |title=From Hot Towers to TRMM: Joanne Simpson and Advances in Tropical Convection Research |journal=Meteorological Monographs |date=January 2003 |volume=29 |issue=51 |pages=37–47 |doi=10.1175/0065-9401(2003)029<0037:CFHTTT>2.0.CO;2 |ref={{sfnRef|Houze (2003)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}} {{open access}}
* {{cite journal |last1=Leppert |first1=Kenneth D. |last2=Petersen |first2=Walter A. |title=Electrically Active Hot Towers in African Easterly Waves prior to Tropical Cyclogenesis |journal=Monthly Weather Review |date=March 2010 |volume=138 |issue=3 |pages=663–687 |doi=10.1175/2009MWR3048.1 |ref={{sfnRef|Leppert and Petersen (2010)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}} {{open access}}
* {{cite journal |last1=Malkus |first1=Joanne S. |last2=Ronne |first2=Claude |last3=Chaffe |first3=Margaret |title=Cloud Patterns in Hurricane Daisy, 1958 |journal=Tellus |date=January 1961 |volume=13 |issue=1 |pages=8–30 |doi=10.3402/tellusa.v13i1.9439 |via=Taylor & Francis Online |ref={{sfnRef|Malkus et al. (1961)}}}} {{open access}}
* {{cite journal |last1=Malkus |first1=Joanne S. |last2=Williams |first2=R. T. |title=On the Interaction between Severe Storms and Large Cumulus Clouds |journal=Severe Local Storms |via=Springer Link |date=September 1963 |volume=5 |pages=59–64 |doi=10.1007/978-1-940033-56-3_3 |ref={{sfnRef|Malkus and Williams (1963)}} |publisher=American Meteorological Society |location=Boston, Massachusetts |isbn=978-1-940033-56-3}}
* {{cite journal |last1=Riehl |first1=Herbert |last2=Malkus |first2=Joanne |title=Some Aspects of Hurricane Daisy, 1958 |journal=Tellus |date=January 1961 |volume=13 |issue=2 |pages=181–213 |doi=10.3402/tellusa.v13i2.9495 |via=Taylor & Francis Online |ref={{sfnRef|Riehl and Malkus (1961)}}}} {{open access}}
* {{cite journal |last1=Montgomery |first1=M. T. |last2=Nicholls |first2=M. E. |last3=Cram |first3=T. A. |last4=Saunders |first4=A. B. |title=A Vortical Hot Tower Route to Tropical Cyclogenesis |journal=Journal of the Atmospheric Sciences |date=January 2006 |volume=63 |issue=1 |ref={{sfnRef|Montgomery et al. (2006)}} |pages=355–386 |doi=10.1175/JAS3604.1 |publisher=American Meteorological Society |location=Boston, Massachusetts}} {{open access}}
* {{cite journal |last1=Tao |first1=Cheng |last2=Jiang |first2=Haiyan |title=Global Distribution of Hot Towers in Tropical Cyclones Based on 11-Yr TRMM Data |journal=Journal of Climate |date=February 2013 |volume=26 |issue=4 |pages=1371–1386 |doi=10.1175/JCLI-D-12-00291.1 |ref={{sfnRef|Tao and Jiang (2013)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}}
* {{cite journal |last1=Williams |first1=E. R. |last2=Geotis |first2=S. G. |last3=Renno |first3=N. |last4=Rutledge |first4=S. A. |last5=Rasmussen |first5=E. |last6=Rickenbach |first6=T. |title=A Radar and Electrical Study of Tropical “Hot Towers” |journal=Journal of the Atmospheric Sciences |date=August 1992 |volume=49 |issue=15 |pages=1386–1395 |doi=10.1175/1520-0469(1992)049<1386:ARAESO>2.0.CO;2 |ref={{sfnRef|Williams et al. (1992)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}} {{open access}}
* {{cite journal |last1=Zhuge |first1=Xiao-Yong |last2=Ming |first2=Jie |last3=Wang |first3=Yuan |title=Reassessing the Use of Inner-Core Hot Towers to Predict Tropical Cyclone Rapid Intensification* |journal=Weather and Forecasting |date=October 2015 |volume=30 |issue=5 |pages=1265–1279 |doi=10.1175/WAF-D-15-0024.1 |ref={{sfnRef|Zhuge et al. (2015)}} |publisher=American Meteorological Society |location=Boston, Massachusetts}}
* {{cite book |last1=Zipser |first1=Edward J. |editor1-last=Tao |editor1-first=Wei-Kuo |editor2-last=Adler |editor2-first=Robert |title=Cloud Systems, Hurricanes, and the Tropical Rainfall Measuring Mission (TRMM) |chapter=Some Views On “Hot Towers” after 50 Years of Tropical Field Programs and Two Years of TRMM Data |date=2003 |pages=49–58 |doi=10.1007/978-1-878220-63-9_5 |ref={{sfnRef|Zipser (2003)}} |publisher=American Meteorological Society |location=Boston, Massachusetts |via=Springer Link |isbn=978-1-878220-63-9}}
{{refend}}


==External links==
==External links==
*[http://www.nasa.gov/vision/earth/lookingatearth/hurricane_multimedia.html Hurricane Multimedia Gallery.] - A Hurricane Multimedia page.
*[http://www.nasa.gov/vision/earth/lookingatearth/hurricane_multimedia.html Hurricane Multimedia Gallery]&nbsp;– a hurricane multimedia page.
*[https://web.archive.org/web/20051025043644/http://www.ucar.edu/pres/simpson/index.htm UCAR slides: "Hot Towers and Hurricanes: Early Observations, Theories and Models"]
*[https://web.archive.org/web/20051025043644/http://www.ucar.edu/pres/simpson/index.htm UCAR slides: "Hot Towers and Hurricanes: Early Observations, Theories and Models"]


{{Cloud types}}
{{Cloud types}}


{{DEFAULTSORT:Hot Tower}}
{{DEFAULTSORT:Hot tower}}
[[Category:Weather hazards]]
[[Category:Weather hazards]]
[[Category:Tropical cyclone meteorology]]
[[Category:Tropical cyclone meteorology]]

Revision as of 19:34, 20 March 2021

A NASA Global Hawk detects a hot tower measuring over 12 km (7.5 mi) high within the eyewall of Hurricane Karl on September 16, 2010.

A hot tower is a tropical cumulonimbus cloud that reaches out of the lowest layer of the atmosphere, the troposphere, and into the stratosphere.[1] These formations are called "hot" because of the large amount of latent heat released as water vapor condenses into liquid and freezes into ice within the cloud. Hot towers in regions of sufficient vorticity may acquire rotating updrafts; these are known as vortical hot towers. The role of hot towers in tropical weather was first formulated by Joanne Simpson in 1958. Hot towers dominated discussions in tropical meteorology in the 1960s and are now considered the main drivers of rising air within tropical cyclones and a major component of the Hadley circulation. Although the prevalence of hot towers in scientific literature decreased in the 1970s, hot towers remain an active area of research. The presence of hot towers in tropical cyclones is correlated with an increase in the tropical cyclones's intensities.[2]

Observation

Hot towers were first detected by radar in the 1950s.[1] Aerial reconnaissance was used to probe hot towers, though planes avoided the most dangerous cores of hot towers due to safety concerns.[3] The launch of the Tropical Rainfall Measuring Mission (TRMM) in 1997 provided the resolution and coverage necessary to systematically catalog hot towers and precisely assess their structure globally.[1] Prior to 1997, the small size and short duration of hot towers limited studies of hot towers to aerial observations as the resolutions of satellite sensors at microwave and infrared wavelengths were to coarse to properly resolve details within hot towers.[4]

Structure

The term hot tower has been applied to both rapidly rising parcels of air and the tall cumulonimbus clouds that accompany them.[1][5] The regions of rising air are horizontally small and span about 2–4 km (1.2–2.5 mi) across.[5][3] Their greatest extent is in the vertical, reaching altitudes as high as 18 km (11 mi) and exhibiting high reflectivity.[6] Hot towers are effectively undilute; as they ascend, the surrounding air does not mix with the rising parcels of air.[7][8] As a result, the equivalent potential temperature within a hot tower remains nearly constant throughout their entire vertical extent. This allows for efficient transport of heat from the lower troposphere to the stratosphere. Hot towers forming within areas of rotation may feature rotating updrafts; these are known as vortical hot towers and are associated with localized regions of anomalous vertical vorticity.[8]

Conceptual development

Aerial studies of Hurricane Daisy in 1958 were pivotal in validating the relationship between hot towers and tropical cyclones

Before the 1950s, the mechanism driving atmospheric Hadley cells—an air circulation that transports tropical heat and moisture poleward—was poorly understood.[9] It was initially believed that the Hadley cell was fueled by the broad, diffuse, and gradual rise of warm and moist air near the equator. However calculations of Earth's energy budget using data from World War II showed that the mid-troposphere was an energy deficit region, indicating that the maintenance of the Hadley cell could not be explained by the broad ascent of air.[3] The role of the tropical regions in the global climate system and the development of tropical disturbances were also poorly understood. The 1950s marked a pivotal decade that saw the advancement of tropical meteorology, including the creation of the U.S. National Hurricane Research Project in 1956.[10] In 1958, Herbert Riehl and Joanne Simpson proposed that the release of latent heat caused by condensation within hot towers supplied the energy necessary to maintain Hadley cells and the trade winds; their hypothesis was initially based on aerial observations made by Simpson during her time at Woods Hole Oceanographic Institution.[9] This mechanism required the existence of undilute cumulonimbus clouds that did not entrain the surrounding air, allowing for the efficient transfer of heat from the ocean surface into the upper troposphere.[11] The existence of 1,500–2,500 of these clouds was required if they were to support the Hadley circulation.[3] The resarchers also argued that hot towers helped maintain the warmth present at the center of tropical cyclones and that the ascent of moist air within tropical cyclones was concentrated around the hot towers.[12] In their original 1958 paper outlining the role of hot towers, Riehl and Simpson described these clouds as "narrow warm towers", but began terming the idea as the "hot tower hypothesis" by 1960.[11][9] For the next two decades, hot towers dominated scientific discussion concerning the interaction between cumulus clouds and their larger-scale tropical environments.[10]

Visualization of moisture concentrations in a hurricane
Visualization of a hot tower in Hurricane Bonnie (1998). Cloud heights are exaggerated.

Aerial observations of Hurricane Daisy in 1958 suggested that convection within tropical cyclones was limited to a few areas of cumulonimbus clouds, dispelling the idea that rising air was distributed throughout the entire cyclone's envelope and lending support for the hot tower hypothesis.[11] In the case of Hurricane Daisy, the convecting cumulonimbus clouds represented only about four percent of the total region of precipitation associated with the hurricane. A 1961 analysis by Riehl and Simpson using the NHRP data from Hurricane Daisy concluded that hot towers were the principal mechanism by which tropical cyclones move warm air into the upper troposphere. The newfound importance of hot towers in tropical cyclones motivated the development of parametrization—the representation of small-scale phenomena and interactions, i.e. individual cumulus clouds—in early weather models.[13] The hot tower hypothesis also inspired the development of convective instability of the second kind (CISK): a conceptual model that emphasized the feedbacks between the latent heat released by individual cumuli and the convergence associated with tropical cyclones.[14] By the 1970s, many of the ideas and predictions put forth by the hot tower hypothesis had been validated by empirical observations.[8] Critics of the hot tower hypothesis contended it was implausible that a cumulonimbus cloud could be free of entrainment.[9] This facet of the hypothesis remained untested until dropsondes released into hot towers as part of the Convection and Moisture Experiment in 1998 provided the first direct measurements of the thermodynamic structure of hot towers. The data showed that the equivalent potential temperature within hot towers was virtually constant across their entire vertical extent, confirming the lack of entrainment.[8] Other field observations have suggested that some tropical updrafts are diluted by their surrounding environments at altitudes lower than 5 km (3.1 mi), though strong latent heat generated by ice within the cloud was sufficient to provide the requisite input energy for the Hadley circulation.[15] Scientific research of hot towers experienced a resurgence in the 2000s with a renewed focus on their role in tropical cyclogenesis and tropical cyclone development.[5]

Effect on tropical cyclones

Vortical hot towers aid in the formation of tropical cyclones by producing many small-scale positive anomalies of potential vorticity, which eventually coalesce to strengthen the broader storm.[16] The high vorticity present in the hot towers traps the latent heat released by those clouds, while the merger of the hot towers aggregates this enhanced warmth.[17] These processes are the major part of the initial formation of a tropical cyclone's warm core—the anomalous warmth at the center of such a system—and the increased angular momentum of the winds encircling the developing cyclone.[16]

In 2007, the National Aeronautics and Space Administration (NASA) hypothesized that the wind shear between the eye and the eyewall could enhance updraft through the center of a cyclone and generate convection.[18] Hot towers may appear when a cyclone is about to intensify, possibly rapidly. A particularly tall hot tower rose above Hurricane Bonnie in August 1998, as the storm intensified before striking North Carolina.[19]

See also

References

  1. ^ a b c d Voiland, Adam (12 September 2012). "Discovering Hot Towers". Earth Observatory. NASA. Retrieved 16 March 2021.
  2. ^ Chohan, Rani. "Scientists Discover Clues to What Turns a Hurricane into a Monster". 12 January 2004: NASA. Retrieved 16 March 2021.{{cite web}}: CS1 maint: location (link)
  3. ^ a b c d Fierro et al. (2009), p. 2731.
  4. ^ Perkins, Lori (15 September 2005). "Hurricane Katrina Hot Towers". Scientific Visualization Studio. NASA. Retrieved 16 March 2021.
  5. ^ a b c Guimond et al. (2010), p. 634.
  6. ^ Heymsfield et al. (2010), p. 286.
  7. ^ Montgomery et al. (2006), p. 356.
  8. ^ a b c d Anthes (2003), p. 144.
  9. ^ a b c d Weier, John (April 28, 2004). ""Hot Tower" Hypothesis". Joanne Simpson (1923–2010). NASA. Retrieved 16 March 2021. {{cite book}}: |website= ignored (help)
  10. ^ a b Anthes (2003), p. 139.
  11. ^ a b c Anthes (2003), p. 140.
  12. ^ Weier, John (April 28, 2004). "Warm Core Mystery". Joanne Simpson (1923–2010). NASA. Retrieved 16 March 2021. {{cite book}}: |website= ignored (help)
  13. ^ Anthes (2003), p. 141.
  14. ^ Anthes (2003), p. 143.
  15. ^ Fierro et al. (2009), p. 2745.
  16. ^ a b Hendricks et al. (2004), p. 1209.
  17. ^ Hendricks et al. (2004), p. 1229.
  18. ^ National Aeronautics and Space Administration (2007). "Hot towers simulation". NOAA. Retrieved 2009-09-18.
  19. ^ National Climatic Data Center (1998). "Bonnie Buffets North Carolina!". NOAA. Archived from the original on 2008-09-16. Retrieved 2009-01-07.

Bibliography

  • Anthes, Richard A. (2003). "Hot Towers and Hurricanes: Early Observations, Theories, and Models". In Tao, Wei-Kuo; Adler, Robert (eds.). Cloud Systems, Hurricanes, and the Tropical Rainfall Measuring Mission (TRMM). Boston, Massachusetts: American Meteorological Society. pp. 139–148. doi:10.1007/978-1-878220-63-9_10. ISBN 978-1-878220-63-9 – via Springer Link.
  • Fierro, Alexandre O.; Simpson, Joanne; LeMone, Margaret A.; Straka, Jerry M.; Smull, Bradley F. (September 2009). "On How Hot Towers Fuel the Hadley Cell: An Observational and Modeling Study of Line-Organized Convection in the Equatorial Trough from TOGA COARE". Journal of the Atmospheric Sciences. 66 (9). Boston, Massachusetts: American Meteorological Society: 2730–2746. doi:10.1175/2009JAS3017.1. Open access icon
  • Guimond, Stephen R.; Heymsfield, Gerald M.; Turk, F. Joseph (March 2010). "Multiscale Observations of Hurricane Dennis (2005): The Effects of Hot Towers on Rapid Intensification". Journal of the Atmospheric Sciences. 67 (3). Boston, Massachusetts: American Meteorological Society: 633–654. doi:10.1175/2009JAS3119.1. Open access icon
  • Hendricks, Eric A.; Montgomery, Michael T.; Davis, Christopher A. (June 2004). "The Role of "Vortical" Hot Towers in the Formation of Tropical Cyclone Diana (1984)". Journal of the Atmospheric Sciences. 61 (11). Boston, Massachusetts: American Meteorological Society: 1209–1232. doi:10.1175/1520-0469(2004)061<1209:TROVHT>2.0.CO;2. Open access icon
  • Heymsfield, Gerald M.; Tian, Lin; Heymsfield, Andrew J.; Li, Lihua; Guimond, Stephen (1 February 2010). "Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar". Journal of the Atmospheric Sciences. 67 (2). Boston, Massachusetts: American Meteorological Society: 285–308. doi:10.1175/2009JAS3132.1.
  • Houze, Robert A. Jr. (January 2003). "From Hot Towers to TRMM: Joanne Simpson and Advances in Tropical Convection Research". Meteorological Monographs. 29 (51). Boston, Massachusetts: American Meteorological Society: 37–47. doi:10.1175/0065-9401(2003)029<0037:CFHTTT>2.0.CO;2. Open access icon
  • Leppert, Kenneth D.; Petersen, Walter A. (March 2010). "Electrically Active Hot Towers in African Easterly Waves prior to Tropical Cyclogenesis". Monthly Weather Review. 138 (3). Boston, Massachusetts: American Meteorological Society: 663–687. doi:10.1175/2009MWR3048.1. Open access icon
  • Malkus, Joanne S.; Ronne, Claude; Chaffe, Margaret (January 1961). "Cloud Patterns in Hurricane Daisy, 1958". Tellus. 13 (1): 8–30. doi:10.3402/tellusa.v13i1.9439 – via Taylor & Francis Online. Open access icon
  • Malkus, Joanne S.; Williams, R. T. (September 1963). "On the Interaction between Severe Storms and Large Cumulus Clouds". Severe Local Storms. 5. Boston, Massachusetts: American Meteorological Society: 59–64. doi:10.1007/978-1-940033-56-3_3. ISBN 978-1-940033-56-3 – via Springer Link.
  • Riehl, Herbert; Malkus, Joanne (January 1961). "Some Aspects of Hurricane Daisy, 1958". Tellus. 13 (2): 181–213. doi:10.3402/tellusa.v13i2.9495 – via Taylor & Francis Online. Open access icon
  • Montgomery, M. T.; Nicholls, M. E.; Cram, T. A.; Saunders, A. B. (January 2006). "A Vortical Hot Tower Route to Tropical Cyclogenesis". Journal of the Atmospheric Sciences. 63 (1). Boston, Massachusetts: American Meteorological Society: 355–386. doi:10.1175/JAS3604.1. Open access icon
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  • Williams, E. R.; Geotis, S. G.; Renno, N.; Rutledge, S. A.; Rasmussen, E.; Rickenbach, T. (August 1992). "A Radar and Electrical Study of Tropical "Hot Towers"". Journal of the Atmospheric Sciences. 49 (15). Boston, Massachusetts: American Meteorological Society: 1386–1395. doi:10.1175/1520-0469(1992)049<1386:ARAESO>2.0.CO;2. Open access icon
  • Zhuge, Xiao-Yong; Ming, Jie; Wang, Yuan (October 2015). "Reassessing the Use of Inner-Core Hot Towers to Predict Tropical Cyclone Rapid Intensification*". Weather and Forecasting. 30 (5). Boston, Massachusetts: American Meteorological Society: 1265–1279. doi:10.1175/WAF-D-15-0024.1.
  • Zipser, Edward J. (2003). "Some Views On "Hot Towers" after 50 Years of Tropical Field Programs and Two Years of TRMM Data". In Tao, Wei-Kuo; Adler, Robert (eds.). Cloud Systems, Hurricanes, and the Tropical Rainfall Measuring Mission (TRMM). Boston, Massachusetts: American Meteorological Society. pp. 49–58. doi:10.1007/978-1-878220-63-9_5. ISBN 978-1-878220-63-9 – via Springer Link.

External links

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