[ELI5] How come air can extinguish a fire (e.g. blowing a candle) but also ignite it (e.g. blowing a spark)?

Question

[ELI5] How come air can extinguish a fire (e.g. blowing a candle) but also ignite it (e.g. blowing a spark)?

In: 2

Answer 1

It becomes a balance issue for the needs of the flame. To have fire, you need oxygen, fuel, and heat. If those are out of balance, you don’t have fire.

When you blow out a candle, you disrupt the balance of oxygen and heat. You provide way too much oxygen and remove the heat.

When you have a spark, it’s surrounded by fuel. A controlled blowing gives it enough oxygen to help ignite the surrounding fuel.