These higher-albedo areas radiate away absorbed energy at night for every rotation of the planet and become a cold trap for volatile. The temperature cycle near the equator (in the diurnal zone) maintains sharp albedo variations between the bright and dark regions. The correlation between the surface compositional distribution of methane (CH4) and nitrogen (N2) and the climate zones is somewhat speculative. CH4 is widely distributed outside the Tombaugh Regio and Cthulhu Regio, possibly at latitudinal bands of the northern boundary of Cthulhu. Conversely, N2 is concentrated in the latitudes above 30°N coinciding with the permanent arctic climate zone which spans from 37°N latitude to the pole. Some areas on Pluto's surface experience both tropical and arctic climate since both of the climate zones oscillate in response to the obliquity cycle. A substantial area falls under tropical arctic climate state due to the oscillation of the climate pattern. The layering of the Al-Idrisi Montes at 37°N latitude is speculated to be formed due to the long-term climate cycle in this latitude. The latitude of 37°N is considered as the boundary latitude involving mixing of the tropical (overhead Sun) and arctic (constant dark winter) seasons.