thundercloud

A more precise estimate would require observing more thunderclouds.

Lightning bolts usually are seen zipping from thunderclouds down toward the ground.

For a moment, the gray plane recalled a thundercloud against the clear blue sky.

So he would have run on forever had not Richard thrust him away and gone in to Musa, with a face dark as a thundercloud.

You know the look he had whenever anything like a thundercloud came up in the sky.

Every one else was smiling and Joe's frown stood out like a black thundercloud in a clear blue sky.

Havill was standing at one end, as gloomy as a thundercloud, and at the other was the unfortunate creditor with his hat on.

Everybody was laughing but the bride, and she looked like a thundercloud.