A scale is usually defined as the ratio between the distance between two particular places on the map and the actual distance between the two places on the actual ground surface.
It is widely used by the geographers while studying a map, in order to explain the relationship between the map distance and the earth's distance. This scale is mentioned in the map, mostly at the bottom of the map.
For example, a map scale of 1:500000, this means that 1 centimeter on the map is equivalent to 5000 meters = 5 kilometers on the ground surface.
The westerlies are the prevailing winds that blow from the west to east in middle latitude between the 30 to 60 degrees.
These are found from the high pressure areas of the horse latitude towards to poles and sheer extra tropical cyclones.
Westerlie are strongest in the winter hemisphere, and at time when the pressure is lower over the poles, while its weakest in summers, there impact on the ocean currents when moving from west to east the western ocean current transports warm tropical water to the poles.
