Waterhoos, windhoos, tornado... Is er wetenschappelijk verschil?
Hier een stukje van Dhr Doswell uit Amerika :
2. Waterspouts, landspouts, and ...?
Having mentioned waterspouts, this raises another topic. There's a special name for a tornado moving over the water: a waterspout. Why do we not have special names for tornadoes moving over sand (sandspout?), or asphalt (tarmacnado?), or mobile homes (manufacturnado?), or eucalyptus trees (gumswirl?)? Is it a waterspout if the water is fresh water rather than sea water? Does it become a waterspout if it moves over a lake? What about a pond? How about encountering a swimming pool or perhaps a puddle? How big does a body of water have to be to create a waterspout from a tornado? What about when crossing a river? A creek? A dry streambed? Would this last example be a "dry waterspout"? I'm engaging deliberately in reductio ad adsurdum here because I don't believe there is any scientific distinction of consequence between a waterspout and a tornado!
In the new Glossary (Glickman 2000), in fact, the definition of a waterspout is now:
Waterspout -- 1. In general, a tornado over a body of water. 2. In its most common form, a nonsupercell tornado over water.
For years, people believed that waterspouts were a distinctly different phenomenon, uniquely associated with tropical and subtropical convection that might not even qualify as cumulonimbus clouds. Of course, some "authorities" knew of the annoying problem of supercell tornadoes over water - recognition of this produced the abominable term: "tornadic waterspout." Of late, it's been observed that phenomena quite comparable to waterspouts arise over the land, leading to another dubious term (that I've used!): "landspout" (by analogy, a "waterspoutic tornado"?). In my opinion, all these terms refer to the same phenomenon: an intense vortex associated with deep moist convection. Thus, I dispute the standard definition for its exclusion of convective vortices that happen with clouds not meeting the criteria to be cumulonimbi (e.g., those without glaciation at the cloud top).
I'm proposing the following revised definition:
Tornado -- A vortex extending upward from the surface at least as far as cloud base (with that cloud base associated with deep moist convection), that is intense enough at the surface to do damage should be considered a tornado.
This is without regard to
the underlying surface,
the existence/non-existence of a condensation cloud from cloud base to the surface,
the depth of the moist convective cloud,
the presence/absence of ice in the upper reaches of the convective cloud,
the occurrence/non-occurrence of lightning within the convective cloud, or even
the intensity of the phenomenon beyond some lower threshold.
Geknipt uit onderstaande link :
Hier een stukje van Dhr Doswell uit Amerika :
2. Waterspouts, landspouts, and ...?
Having mentioned waterspouts, this raises another topic. There's a special name for a tornado moving over the water: a waterspout. Why do we not have special names for tornadoes moving over sand (sandspout?), or asphalt (tarmacnado?), or mobile homes (manufacturnado?), or eucalyptus trees (gumswirl?)? Is it a waterspout if the water is fresh water rather than sea water? Does it become a waterspout if it moves over a lake? What about a pond? How about encountering a swimming pool or perhaps a puddle? How big does a body of water have to be to create a waterspout from a tornado? What about when crossing a river? A creek? A dry streambed? Would this last example be a "dry waterspout"? I'm engaging deliberately in reductio ad adsurdum here because I don't believe there is any scientific distinction of consequence between a waterspout and a tornado!
In the new Glossary (Glickman 2000), in fact, the definition of a waterspout is now:
Waterspout -- 1. In general, a tornado over a body of water. 2. In its most common form, a nonsupercell tornado over water.
For years, people believed that waterspouts were a distinctly different phenomenon, uniquely associated with tropical and subtropical convection that might not even qualify as cumulonimbus clouds. Of course, some "authorities" knew of the annoying problem of supercell tornadoes over water - recognition of this produced the abominable term: "tornadic waterspout." Of late, it's been observed that phenomena quite comparable to waterspouts arise over the land, leading to another dubious term (that I've used!): "landspout" (by analogy, a "waterspoutic tornado"?). In my opinion, all these terms refer to the same phenomenon: an intense vortex associated with deep moist convection. Thus, I dispute the standard definition for its exclusion of convective vortices that happen with clouds not meeting the criteria to be cumulonimbi (e.g., those without glaciation at the cloud top).
I'm proposing the following revised definition:
Tornado -- A vortex extending upward from the surface at least as far as cloud base (with that cloud base associated with deep moist convection), that is intense enough at the surface to do damage should be considered a tornado.
This is without regard to
the underlying surface,
the existence/non-existence of a condensation cloud from cloud base to the surface,
the depth of the moist convective cloud,
the presence/absence of ice in the upper reaches of the convective cloud,
the occurrence/non-occurrence of lightning within the convective cloud, or even
the intensity of the phenomenon beyond some lower threshold.
Geknipt uit onderstaande link :
