Determination of unknown particle charges in a thunder cloud based upon detected electric field vectors

Climatological data about thunderstorms is traditionally collected by balloons or planes traveling through the storm along straight tracts. Such data lends itself to simple 2D representations. The data described in this paper was gathered by a sail plane spiraling in an updraft within a thundercloud. The more complex organization of data samples demands more complex representation methods. This paper describes a system developed using the Visualization Toolkit (VTK) to explore such data. The data consists of several scalar values and a set of vector values associated with positional data on the measuring devices. The goal of this visualization is to explore the location of point charges suggested by the electromagnetic field vectors and determine if any correlation exists between the point charge location and standard cloud microstructure scalar measurements such as temperature. There are several problems associated with visualizing this rather unique set of data. They stem from the fact that the data is a sparse spiraling sample of scalars and vectors. The system allows the track of the plane to be displayed as a line, a tube or a ribbon; scalar values can be displayed as transparent isosurfaces; and the vector data as an arrow plot along that track, given a color that is constant, based on orientation or related to the value of a scalar. Any combination of methods can be used to display the data. A single primitive can be overloaded in many ways, or several different variables can all be displayed simultaneously.