Altitude sickness is a serious health concern for people not acclimatised to high altitudes. Subtropical evergreen forests resembling those of temperate climates flourish in the higher altitudes. Puebla has many different climates owing to its range of altitudes. They typically live in temperate conditions in the mountains with high altitudes. Birds fly at varying altitudes during migration. Okapis inhabit canopy forests at altitudes of . The Andalusian terrain offers a range of altitudes and slopes. The spacecraft would orbit at decreasing altitudes or regimes. Solar proton events can also produce elevated radiation aboard aircraft flying at high altitudes. Most people who travel to high altitudes acclimatize. The okapi inhabits canopy forests at altitudes of . Radar units give information on the altitudes and thicknesses of cirrus clouds. Frogs are typically found at higher, moister altitudes. Hot air balloons are able to fly to extremely high altitudes. Observations show that the ionosphere occupies altitudes from .