Due to licensing, here at CGC we rely on creative commons images. My favorite place to look for CC images is https://search.creativecommons.org/. There you can choose which source (like Pixabay, Google, Flickr, Wikimedia commons for images) and search by keyword. Pixabay is stock-photo quality images mostly while I find Flickr to return the highest quantity of images.
Here’s pixabay’s results for “smoke”.
