Equitorial regions usually form low pressure regions due to the constant solar energy received. The warm equatorial air rises and moves towards the horse latitudes (30 degrees North/South) and cools down rapidly. At the same time, the cooler, denser air at the horse latitudes move towards the equatorial regions, which is of lower pressure. This forms a stable circular system, which is constantly present, brings dry, cool air to the horse latitudes forming desert conditions, and brings warm hotter air to equatorial regions, forming storm and wind systems.