Editing Hail (section)

== Climatology ==
Hail occurs most frequently within continental interiors at mid-latitudes and is less common in the tropics, despite a much higher frequency of thunderstorms than in the mid-latitudes.<ref>{{cite journal|doi=10.1002/met.236|date=January 2011|title=A global hail climatology using the UK Met Office convection diagnosis procedure (CDP) and model analyses| first1= W. H.| last1= Hand | first2= G.| last2= Cappelluti |publisher=Wiley|journal=[[Meteorological Applications]]|volume=18|issue=4|page=446|bibcode = 2011MeApp..18..446H |doi-access=free}}</ref> Hail is also much more common along mountain ranges because mountains force horizontal winds upwards (known as [[orographic lift]]ing), thereby intensifying the updrafts within thunderstorms and making hail more likely.<ref>{{cite web|url=http://www.ga.gov.au/hazards/severeweather/where.jsp|title=Where does severe weather occur?|publisher= Geoscience Australia, Commonwealth of Australia|access-date=2009-08-28|date=2007-09-04|archive-url= https://web.archive.org/web/20090621231613/http://www.ga.gov.au/hazards/severeweather/where.jsp <!--Added by H3llBot-->|archive-date=2009-06-21}}</ref> The higher elevations also result in there being less time available for hail to melt before reaching the ground. One of the more common regions for large hail is across mountainous northern [[India]], which reported one of the highest hail-related death tolls on record in 1888.<ref name="Oliver">{{cite book| first= John E.| last= Oliver| title = Encyclopedia of World Climatology| url = https://books.google.com/books?id=-mwbAsxpRr0C| access-date = 2009-08-28| year = 2005| publisher = Springer| isbn = 978-1-4020-3264-6| page = 401 }}</ref> [[China]] also experiences significant hailstorms.<ref>{{cite journal|title=The characteristics of cloud-to-ground lightning activity in hailstorms over northern China |first1=Dongxia |last1=Liu |first2=Guili |last2=Feng |first3=Shujun |last3=Wu |date=February 2009|journal=Atmospheric Research|volume=91|issue=2–4|pages=459–465|doi=10.1016/j.atmosres.2008.06.016|bibcode = 2009AtmRe..91..459L }}</ref> Central Europe and southern Australia also experience a lot of hailstorms. Regions where hailstorms frequently occur are southern and western [[Germany]], northern and eastern [[France]], southern and eastern [[Benelux]], and northern [[Italy]].<ref name=":0">{{Cite journal |last1=Laviola |first1=Sante |last2=Monte |first2=Giulio |last3=Cattani |first3=Elsa |last4=Levizzani |first4=Vincenzo |date=September 2022 |title=Hail Climatology in the Mediterranean Basin Using the GPM Constellation (1999&ndash;2021) |journal=Remote Sensing |language=en |volume=14 |issue=17 |page=4320 |doi=10.3390/rs14174320 |bibcode=2022RemS...14.4320L |issn=2072-4292 |doi-access=free }}</ref> In southeastern Europe, [[Croatia]] and [[Serbia]] experience frequent occurrences of hail.<ref>{{cite journal|title=Hail characteristics of different regions in continental part of Croatia based on influence of orography|first1= Damir |last1= Počakal |first2= Željko |last2= Večenaj |first3= Janez |last3= Štalec |journal=Atmospheric Research |volume=93|issue=1–3|date=July 2009|doi=10.1016/j.atmosres.2008.10.017|page=516|bibcode = 2009AtmRe..93..516P }}</ref> Some mediterranean countries register the maximum frequency of hail during the Fall season.<ref name=":0" />

In [[North America]], hail is most common in the area where [[Colorado]], [[Nebraska]], and [[Wyoming]] meet, known as "Hail Alley".<ref name= "ncarhail">{{cite web|url=http://www.ucar.edu/communications/factsheets/Hail.html|title=Fact Sheet on Hail|access-date=2009-07-18| first= Rene |last= Munoz |date=2000-06-02|publisher=University Corporation for Atmospheric Research|archive-url= https://web.archive.org/web/20091015141754/http://www.ucar.edu/communications/factsheets/Hail.html|archive-date=2009-10-15}}</ref> Hail in this region occurs between the months of March and October during the afternoon and evening hours, with the bulk of the occurrences from May through September. [[Cheyenne, Wyoming]] is North America's most hail-prone city with an average of nine to ten hailstorms per season.<ref name="Nolanhail"/> To the north of this area and also just downwind of the Rocky Mountains is the [[Hailstorm Alley]] region of [[Alberta]], which also experiences an increased incidence of significant hail events.

Hailstorms are also common in several regions of [[South America]], particularly in the [[temperate zone|temperate latitudes]]. The [[Pampas|central region]] of [[Argentina]], extending from the [[Mendoza Province|Mendoza region]] eastward towards [[Córdoba Province, Argentina|Córdoba]], experiences some of the most frequent hailstorms in the world, with 10-30 storms per year on average.<ref name= "BruickRasmussenandCecil">{{cite journal|title=South American Hailstorm Characteristics and Environments|journal=Monthly Weather Review |date=2019-11-06|volume=147 |issue=12 |pages=4289–4304 |publisher=American Meteorological Society|doi=10.1175/MWR-D-19-0011.1 |last1=Bruick |first1=Zachary S. |last2=Rasmussen |first2=Kristen L. |last3=Cecil |first3=Daniel J. |pmid=32440028 |pmc=7241597 }}</ref> The [[Patagonia]] region of southern Argentina also sees frequent hailstorms, though this may be partially due to graupel (small hail) being counted as hail in this colder region.<ref name="BruickRasmussenandCecil"/> The triple border region between the [[Brazil|Brazilian]] states of [[Paraná (state)|Paraná]], [[Santa Catarina (state)|Santa Catarina]], and Argentina, in [[southern Brazil]] is another area known for damaging hailstorms.<ref name= "TripleBorder">{{cite journal|url=https://www.sciencedirect.com/science/article/abs/pii/S0169809519308932|title=Climatology of hail in the triple border Paraná, Santa Catarina (Brazil) and Argentina|journal=Atmospheric Research |access-date=2024-06-28|date=2020-04-01|volume=234 |doi=10.1016/j.atmosres.2019.104747 |archive-url= https://web.archive.org/web/20240414134418/https://www.sciencedirect.com/science/article/abs/pii/S0169809519308932|archive-date=2024-04-14 |last1=Beal |first1=Alexandra |last2=Hallak |first2=Ricardo |last3=Martins |first3=Leila D. |last4=Martins |first4=Jorge A. |last5=Biz |first5=Guilherme |last6=Rudke |first6=Anderson P. |last7=Tarley |first7=Cesar R. T. |bibcode=2020AtmRe.23404747B }}</ref> Hailstorms are also common in parts of [[Paraguay]], [[Uruguay]], and [[Bolivia]] that border the high-frequency hail regions of northern Argentina.<ref name= "SouthernBrazil">{{cite web|url=https://www.researchgate.net/publication/309366281|title=Climatology of destructive hailstorms in Brazil|access-date=2024-06-28|date=2020-10-01}}</ref> The high frequency of hailstorms in these areas of South America is attributed to the region's orographic forcing of convection, combined with moisture transport from the Amazon and instability created by temperature contrasts between the surface and upper atmosphere.<ref name="BruickRasmussenandCecil"/> In [[Colombia]], the cities of [[Bogotá]] and [[Medellín]] also see frequent hailstorms due to their high elevation. [[Southern Chile]] also sees persistent hail from mid april through october. 

[[File:Three body scatter spike-NOAA.png|thumb|Example of a three-body spike: the weak triangular echoes (pointed by the arrow) behind the red and white thunderstorm core are related to hail inside the storm.]]

=== Short-term detection ===
[[Weather radar]] is a very useful tool to detect the presence of hail-producing thunderstorms. However, radar data has to be complemented by a knowledge of current atmospheric conditions which can allow one to determine if the current atmosphere is conducive to hail development.

Modern radar scans many angles around the site. Reflectivity values at multiple angles above ground level in a storm are proportional to the precipitation rate at those levels. Summing reflectivities in the [[Vertically Integrated Liquid]] or VIL, gives the [[liquid water content]] in the cloud. Research shows that hail development in the upper levels of the storm is related to the evolution of VIL. VIL divided by the vertical extent of the storm, called VIL density, has a relationship with hail size, although this varies with atmospheric conditions and therefore is not highly accurate.<ref>{{cite web|url=http://www.srh.noaa.gov/hgx/projects/hail_study.htm|title=VIL density and Associated Hail Size Along the Northwest Gulf Coast| first1= Charles A. |last1= Roeseler | first2= Lance |last2= Wood |publisher= National Weather Service Southern Region Headquarters| date= 2006-02-02 |access-date= 2009-08-28|archive-url = https://web.archive.org/web/20070818231127/http://www.srh.noaa.gov/hgx/projects/hail_study.htm |archive-date = August 18, 2007 }}</ref> Traditionally, hail size and probability can be estimated from radar data by computer using algorithms based on this research. Some algorithms include the height of the freezing level to estimate the melting of the hailstone and what would be left on the ground.

Certain patterns of reflectivity are important clues for the meteorologist as well. The [[three body scatter spike]] is an example. This is the result of energy from the radar hitting hail and being deflected to the ground, where they deflect back to the hail and then to the radar. The energy took more time to go from the hail to the ground and back, as opposed to the energy that went directly from the hail to the radar, and the echo is further away from the radar than the actual location of the hail on the same radial path, forming a cone of weaker reflectivities.

More recently, the [[Dual polarization|polarization]] properties of weather radar returns have been analyzed to differentiate between hail and heavy rain.<ref>{{cite journal |first1=K. |last1=Aydin |first2=T.A. |last2=Seliga |first3=V. |last3=Balaji |date=October 1986 |title=Remote Sensing of Hail with a Dual Linear Polarization Radar |journal=Journal of Climate and Applied Meteorology |volume=25 |issue=10 |pages=1475–14 |doi=10.1175/1520-0450(1986)025<1475:RSOHWA>2.0.CO;2 |issn=1520-0450|bibcode = 1986JApMe..25.1475A  |doi-access=free }}</ref><ref>{{cite web| url= http://www.chill.colostate.edu/w/Hail_signature_development|title=Hail Signature Development |publisher= CHILL National Radar Facility, [[Colorado State University]]| date=2007-08-22|access-date=2009-08-28|archive-url= https://web.archive.org/web/20090107012923/http://chill.colostate.edu./w/Hail_signature_development|archive-date=2009-01-07}}</ref> The use of differential reflectivity (<math>Z_{dr}</math>), in combination with horizontal reflectivity (<math>Z_{h}</math>) has led to a variety of hail classification algorithms.<ref>{{cite web|url=http://www.chill.colostate.edu/w/Hydrometeor_classification_example|title=Hydrometeor classification example| publisher= CHILL National Radar Facility, Colorado State University |date=2008-08-25|access-date=2009-08-28|archive-url= https://web.archive.org/web/20100624185402/http://chill.colostate.edu/w/Hydrometeor_classification_example|archive-date=2010-06-24}}</ref> Visible satellite imagery is beginning to be used to detect hail, but false alarm rates remain high using this method.<ref>{{cite journal|doi=10.1016/S0169-8095(96)00032-4|date=1998-07-25|title=Satellite data based detection and prediction of hail|last1=Bauer-Messmer| first1= Bettina| last2= Waldvogel| first2= Albert|journal=Atmospheric Research|volume=43|issue=3|page=217|bibcode = 1997AtmRe..43..217B }}</ref>