What causes the air to move from place to place?
Heat causes the air to move from place to place.
When air is heated, what change takes place?
The heated air ascends, and colder air moves in to fill its place; thus causing the wind to blow.
What illustration have we of this?
When a candle is held in the open door of a heated room, its flame is blown outwards if placed at the top of the door, and inwards if placed at the bottom of the door; thus showing two currents of air.
Why is this?
The heated air escapes from the top of the room, so as to ascend higher, while the colder air comes in at the bottom, to fill its place.
Why does the wind blow towards a fire in the open air?
Because the air near the fire becomes heated, and ascends rapidly, so that the air rushes in from every direction to fill its place.