As defined by A. Supan (1879), a region of the earth within which the mean temperature of the warmest month is less than 10C. This limiting condition closely approximates the temperature at the arctic
tree line, and was later adopted by W. Köppen (1918) as his boundary between the polar climates and tree climates. Supan also defined temperate belt and hot belt in his early form of climatic classification.
Any hypothetical non-baryonic dark matter that is non-relativistic at the point of decoupling in the early Universe. CDM plays a key role in cosmic structure formation.
Any hypothetical non-baryonic dark matter that is non-relativistic at the point of decoupling in the early Universe. CDM plays a key role in cosmic structure formation.
Desert found in the high latitudes and at high altitudes where precipitation is low. Surface air temperatures are generally cold in these dry environments.
Any nonoccluded front, or portion thereof, that moves so that the colder air replaces the warmer air; that is, the leading edge of a relatively cold air mass.