Latitude provides the location of a place north or south of the equator and is expressed by angular measurements ranging from 0° at the equator to 90° at the poles. Different latitudes on Earth receive different amounts of sunlight, and excepting the planetary distribution of land and sea, latitude is the main factor determining a region's climate.
The Earth's axis of rotation is tilted art 23.5° to the perpendicular. This means that the amount of sunlight a particularly latitude receives changes with seasons. From April to September, the Northern Hemisphere is tilted towards the Sun, and consequently receives more energy. During October to March, the Southern Hemisphere is tiled towards the Sun, and summer in the Southern Hemisphere occurs at this time. During the Northern Hemisphere summer, the North Pole receives 24 hours daylight, whilst the South Pole experiences 24 hours darkness. During the other half of the year, the reverse is true. Despite the six months of continuous sunlight however, temperature at the poles remains low rarely rising above freezing because the Sun is never more than 23.5° above the horizon.
More sunlight is received at latitudes nearer the equator than near the poles where the midday angle of incidence of radiation is greater. At the equinoxes, the midday Sun is directly overhead along the equator. The overhead midday Sun annually drifts north and south with the seasons between the Tropic of Cancer (at 23.5° north) and the Tropic of Capricorn (at 23.5° south). The greater amounts of sunlight at lower latitudes keep the climates there warm throughout the year. North and south of about 45° latitude, the angle of the Sun at midday during the winter months is too low to allow appreciable amounts of sunlight to heat the Earth there, and temperatures at this time of year can fall below freezing.