Met een heel dun laagje vocht kun je enorme Cape waarden krijgen, maar de totale hoeveelheid vocht kan nog te laag zijn voor onweer.
Ja, en om deze situaties te herkennen kun je de CAPE waarden vergelijken met de Integrated CAPE (ICAPE) waarden.
Hier de uitleg uit de 'Guide to using convective weather maps' van Oscar van der Velde. De kaartjes zijn te vinden op lightningwizard.com/maps
ICAPE stands for Integrated CAPE, and has the units J/m2, not J/kg. It was first defined
by Mapes (1993) as the sum of CAPE*dp/g for all parcels in a column which have
CAPE>0. This makes it independent of the choice of parcel. Instead, a deeper layer of
parcels that have CAPE gives higher values for the same CAPE than if only a shallow
layer has CAPE. For example, a 100 hPa thick layer giving 500 J/kg CAPE will result in
the same ICAPE value as a shallower 50 hPa layer of 1000 J/kg (about 500 kJ/m2). The
parameter is plotted experimentally, as its advantage over other versions of CAPE in
operational meteorology has never been tested.
It makes sense that if as a storm develops, all air from low levels will be taken into the
storm, and the total energy released by all parcels in a column of one square meter
diameter is ICAPE. In practice, the map will look very similar to MLCAPE, except when
parcel layer thickness differs over the area, or when elevated parcels over a stable
boundary layer have CAPE, where MLCAPE may be absent. So, this parameter has
characteristics of both MLCAPE and MUCAPE.
Groeten,
Bas
Bericht laatst bijgewerkt: 09-04-2009 12:54
