Fire spread associated with violent pyrogenic convection is highly unpredictable and difficult to suppress. Wildfire-driven convection may generate cumulonimbus (storm) clouds, also known as pyrocumulonimbus (pyroCb). Research into such phenomena has tended to treat the fire on the surface and convection in the atmosphere above as separate processes. We used a numerical model to examine the effect of fire geometry on the height of a pyroconvective plume, using idealised model runs in a neutral atmosphere. The role of geometry was investigated because large areal fires have been associated with the development of pyroCb. Complementary results (detailed in Part I) are extended by considering the effect that fire shape can have on plume height by comparing circular, square, and rectangular fires of varying length and width, representing the difference between firelines and areal fires. Results reveal that the perimeter/area ratio influenced the amount of entrainment that the plume experiences and therefore the height to which the plume rises before it loses buoyancy. These results will aid in the prediction of blow-up fires (whereby a fire exhibits a rapid increase in rate of spread or rate of spread) and may therefore be useful in determining where fire agencies deploy their limited resources.

剧烈的热源对流引起的火势蔓延高度难以预测，难以扑灭。由野火驱动的对流可能会产生积雨云（暴风云），也称为焦积雨云（pyroCb）。对这种现象的研究倾向于将表面的火和上方大气中的对流视为单独的过程。我们使用数值模型来检查火场几何形状对热对流羽流高度的影响，方法是在中性气氛中使用理想化模型运行。对几何形状的作用进行了研究，因为大面积的火灾与pyroCb的发展有关。通过比较不同长度和宽度的圆形，方形和矩形火，考虑了火形状对烟羽高度的影响，可以扩展补充结果（在第I部分中详细介绍），代表着火线和区域火之间的差异。结果表明，周长/面积比影响羽流所经历的夹带量，从而影响羽流失去浮力之前上升的高度。这些结果将有助于预测爆炸性大火（从而使大火的蔓延速度或蔓延速度迅速增加），因此在确定消防机构将有限资源部署到何处时可能很有用。