system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What causes the noise a flame makes when blowing in the wind?
gpt
When something burns it isn't actually the solid or liquid that burns. It first off gases or evaporates creating a gas that is flammable. This gas however is too rich to burn immediately it rises and mixes with air until it makes a mix that can burn. If you look at a log for example you will see a very small space between the surface of the log and where the flame starts. When you blow or the wind blows you increase this mixing of flammable gas and oxygen creating a more rapid burning that essentially creates a series of small explosions.

Edit: the crackle too is due to more rapid boiling of pockets of water in the wood which causes it to expand and pop the structure it is contained in.