Marilyn Maxon, age 12, of Fredericton, New Brunswick, Canada, for her question:

What is meant by a horse latitude?

A latitude, of course, is a global circle parallel with the Equator. From pole to pole, climate zones and wind belts create special conditions along certain latitudes. These conditions were vitally important to old time sailing ships. Latitudes 40 degrees North and South of the equator are stormy zones    and sailors called them the Roaring Forties. They also named Latitudes 30 degrees North and South the Horse Latitudes. These calm regions of descending air are between the global belts of the trade winds and the prevailing westerlies.

The Horse Latitudes are warm, high pressure zones with few clouds, few breezes and long periods of calm. In the Atlantic, Spanish sailing ships were often becalmed in these waters. With no breezes to fill their sails, they often waited for weeks while food and water ran low. Unable to provide for the horses on board, they had to throw the animals into the sea. It is assumed that this is why these suffocating zones were named the Horse Latitudes.