Latitude. The climate of any region is largely determined by the region's relation to the sun, which is called latitude, as well as its relation to water, winds, and elevation. Latitude is the most obvious and sometimes most deceptive determinant of climate. The southern extremes of Europe, such as Barcelona and Rome, are at a latitude equal to northern portions of the United States, such as New York. But the European climate of Madrid and Rome is much warmer than that of New York due to ocean currents and high-altitude winds known as the jetstreams. Most of Europe has a mild, temperate, and humid climate. Temperate-zone climates have a pronounced difference between winter and summer conditions. The most notable exception is the snow forest climate in some portions of Scandinavia.

Ocean and Wind Currents. Europe, the only continent with no desert region, is a peninsula jutting...