Winds are named for the direction from which they blow. A southerly wind blows from the south. An easterly wind blows from the east. The prevailing westerlies blow across much of Canada. Weather announcers often talk about the wind chill factor. Wind chill is the estimate of how cold the wind makes people feel. A strong northerly wind will make the temperature seem colder than it would be with no wind.

Most of the moisture in the air comes from the oceans. Water evaporates from oceans and lakes and rises into the air. The amount of water vapour in the air is called humidity. The more moisture in the air, the higher the humidity. Air that holds as much moisture as it can is said to be saturated. The temperature at which the air becomes saturated is called the dew point. If the temperature fails below the dew point, the moisture in the air condenses. When this happens, drops of water settle on grass, leaves, windows and other surfaces. These drops of water are called dew. If the dew point is at or below freezing, we get frost. When warm, moist air near the ground is cooled to its dew point, we may get fog. When the air cools, we may get precipitation, such as rain or snow.

How did the horse latitudes get their name? The prevailing westerlies are winds which blow across most of Canada. The trade winds blow from the north and south and meet near the equator. There is an area between the prevailing westerlies and the trade winds called the horse latitudes. The winds in the horse latitudes are very light. Early Spanish sailors brought horses to America. The Spanish sailing ships sometimes became stalled in the light winds of the area. When the sailors ran out of water for the horses, they would throw the horses overboard.