ENVI-met

ENVI-met is a three-dimensional microclimate model designed to simulate the surface-plant-air interactions in urban environment with a typical resolution of 0.5 to 10 m in space and 10 sec in time.

Typical areas of application are Urban Climatology, Architecture, Building Design or Environmental Planing, just to name a few.
ENVI-met is a Freeware program based on different scientific research projects and is therefore under constant development. ENVI-met is NOT Open Source.
ENVI-met comes along with a number of additional software ranging from an editors up to graphical visualization tools for the model results.