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- Author or Editor: Giorgio M. Caranti x
- Journal of the Atmospheric Sciences x
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Abstract
The dependence on liquid water content (LWC) and temperature (T) of the charge transfer, and in particular its sign, during ice crystal–graupel collisions is a matter of controversy. Some of the laboratory measurements do not agree on the general shape of this function, although they agree on the existence of a critical temperature T r , above which there is one sign and below which the opposite one. In this paper, the authors carry out a numerical study to investigate the behavior of three charging parameterizations in thunderstorm electrification. This study is carried out on one cloud case study, and a limited set of T–LWC values are present. Surprisingly, the general behavior is the same among the three, despite the distinct differences in the charging diagrams.
Abstract
The dependence on liquid water content (LWC) and temperature (T) of the charge transfer, and in particular its sign, during ice crystal–graupel collisions is a matter of controversy. Some of the laboratory measurements do not agree on the general shape of this function, although they agree on the existence of a critical temperature T r , above which there is one sign and below which the opposite one. In this paper, the authors carry out a numerical study to investigate the behavior of three charging parameterizations in thunderstorm electrification. This study is carried out on one cloud case study, and a limited set of T–LWC values are present. Surprisingly, the general behavior is the same among the three, despite the distinct differences in the charging diagrams.
Abstract
Charge transfer between colliding ice particles is measured using a wind tunnel inside a cold room. A cylinder growing by riming in a wind tunnel was used as a target for collisions between 5 and 6 m s−1 with ice spheres of 100-µm diameter. The target temperature was adjusted to simulate different liquid water concentrations. As the target temperature increased, for air temperatures below −18°C, initial positive target charging reversed sign to negative; with a further temperature increase the charging reversed sign again. These measurements, which are relevant to thunderstorm electrification, were carried out with and without riming and results are compared with other works. A novel approach is presented here suggesting a new pair of variables describing the charging.
Abstract
Charge transfer between colliding ice particles is measured using a wind tunnel inside a cold room. A cylinder growing by riming in a wind tunnel was used as a target for collisions between 5 and 6 m s−1 with ice spheres of 100-µm diameter. The target temperature was adjusted to simulate different liquid water concentrations. As the target temperature increased, for air temperatures below −18°C, initial positive target charging reversed sign to negative; with a further temperature increase the charging reversed sign again. These measurements, which are relevant to thunderstorm electrification, were carried out with and without riming and results are compared with other works. A novel approach is presented here suggesting a new pair of variables describing the charging.
