The map that is show was a map that was probably made and used by meteorologists. It is a map that that shows isobars, thus it is a map that represents the air pressures across the US and Canada. We can see the air pressure zones, some of which high, some of which low. These maps are often used when the weather information is concluded about certain areas, as the air pressure is directly connected with the temperature, and the movement of the air masses.
