| A thundercloud, with a distinctive upper anvil shape, results from air which is moist and unstable rising by convection. |
| As you pointed out, it takes about 800 million volts to get lightning to jump between a thundercloud and the ground. |
| Oh, yeah, we were still in a thick thundercloud with periodic flashes of lightning surrounding us. |
| A company in the USA have now produced a gel that they claim is able to almost totally destroy a building thundercloud. |
| The top of a cumulonimbus cloud is often capped by cirrus, which is why the anvil of a thundercloud is often brilliant white. |
| A funnel cloud at the rear base of a thundercloud, often behind a curtain of heavy rain or hail. |
