You have seen that a flame from a candle light always points upwards. It will point upwards even if you tilted the candle. Ever wondered why it is happening?
The effect that you see here is a result gravity and atmospheric pressure. As the candle flame is hot it increases the surrounding air temperature.
When the atmospheric gases near the candle flame get heated up it begins to lose its density and starts to move upwards. At the same time the surrounding
colder air will come down due to gravity. This causes a swirling effect which make the candle flame to point upwards.
Scientists have conducted the same experiment in space where there is no gravity and the resultant flame is a spherical one.
Courtesy: https://en.wikipedia.org/wiki/International_Space_Station, https://www.quora.com/Why-does-a-flame-always-point-upwards