Solution:The horse latitudes are located at about 30° to 35° north and south of the Equator. In the northern hemisphere it is called as the north sub-tropical high-pressure belt and in the southern hemisphere, it is known as the south sub-tropical high-pressure belt.The existence of these pressure belts is due to the fact that the rising air of the equatorial region is deflected towards poles due to the earth's rotation. After becoming cold and heavy, it descends in these regions due to earth rotation and get piled up.
This results in high pressure. Calm conditions with feeble and variable winds are found here. In ancient times vessels with a cargo of horses passing through these belts found difficulty in sailing under these calm conditions.
They used to throw a few horses in the sea in order to make the vessels lighter. Thus, these belts or latitudes came to be known as 'horse latitudes'.