In the temperate forests, the average annual temperature is 50 degrees F, while the average rainfall is generally high ranging from 30 to 60 inches per year. Wind is a big factor of why temperature and climate change so frequently. The Westerlies are winds that blow from the West and are the reason for drastic temperature changes. One of the most abundant types of soil is alfisol which includes a top layer of primarily dead leaves and a subsoil which has a high concentration of clay. Ultisols are another type of soil which provide poor aeration and lack nutrients. Rocky soil is also present but is dry and infertile. Sandy soil exists and is very low in nutrients and is poor at retaining water, but some trees like pitch pines can thrive in this soil. In general though, deciduous forests are deep and rich in nutrients. A distinctive physical feature is its changing seasons. It also includes mountains, valleys, rolling hills and flat plateaus in the Northern Hemispheres. In the Southern Hemisphere, deciduous forests tend to grow in grasslands where the land is nearly level.