| Abstract | The Markowski-toy-model.tar file contains the FORTRAN code for the “toy model” version of CM1 (also known as the Bryan Cloud Model) used in a series of journal articles from 2014–2017 by Paul Markowski and collaborators. These articles presented the results of “pseudostorms” generated by a heat source and sink in a vertically sheared environment. The model can reproduce many aspects of the supercell thunderstorms observed in nature. The heat source drives an updraft that rotates cyclonically owing to the upward tilting of the streamwise horizontal vorticity imposed in the environment. The heat sink, centered northeast of the heat source, drives a downdraft that mimics the precipitation-driven downdraft of an actual storm.
A tornadolike vortex develops at the lowest model level if circulation-rich, near-surface air is associated with weak negative buoyancy and also experiences a large upward-directed vertical perturbation pressure-gradient force owing to its proximity to the overlying heat source and associated midlevel updraft and mesocyclone. This is most likely to happen when the heat sink is of intermediate strength and the environmental low-level shear is strong.
It is assumed that the user is familiar with CM1. Documentation for CM1 can be obtained at http://www2.mmm.ucar.edu/people/bryan/cm1/.
|
