<span>The fluid flows through the interventricular foramen into the third ventricle, is augmented by fluid formed by the choroid plexus of this ventricle, and passes through the cerebral aqueduct to the fourth ventricle, which also possesses a choroid plexus. The CSF from all theses sources , as well as any formed in the central canal of the spinal cord, escapes from the fourth ventricle into the subarachnoid space through the median aperture and lateral aperture.</span>
They are based on their temperature and precipitation according to the <span>Köppen Climate Classification System</span>