On a day like today, when the temperature in Toronto as recorded at Pearson Airport is 28 degrees Celsius before humidity is taken into account and 38 degrees Celsius after, I was curious to find out how fans actually work. Convection is the relevant principle. The motion of the fan causes air to circulate within a specific area. If this air is cooler than a particular object--say, your skin--it will absorb this second object's heat and rise. Because hot air rises, cooler air moves in to take its place and absorb more warmth. The faster this convecting air moves, the cooler you feel.