We are familiar with how flames burn. Let it be a tear shaped candle flame or a forest fire, it always burns upwards. We will look into the details later, but the following image released by NASA says it all
Gravity does the magic:
Its obvious from the above illustration that gravity has a role to play. However, one can’t help but wonder why a flame would go upwards where there is strong gravitation pull like on earth and remain spherical where there is no gravity like on a space station. The answer is buoyancy.