The reason mountains need their own climate type is because the climate changes as you move up the mountain. At the base (bottom) of a mountain it might be 80 degrees and sunny, but as you climb the mountain it will get colder and be rainy.he type of vegetation that grows in Highland also depends on the elevation. At the base (bottom) of the mountain the vegetation will be the same as the surrounding climate type. So, a mountain in the rainforest will have rainforest at the base.