päivänpituus

Päivänpituus, or day length, refers to the duration of daylight in a given location on a specific day. It is influenced by several factors, including the Earth's axial tilt, its orbit around the Sun, and the rotation of the Earth on its axis. The length of daylight varies throughout the year due to the Earth's axial tilt, which causes the Northern and Southern Hemispheres to receive more or less direct sunlight at different times of the year.

The day length is longest around the summer solstice, which occurs on June 21st in the Northern Hemisphere and December 21st in the Southern Hemisphere. At this time, the North Pole is tilted towards the Sun, resulting in the longest period of daylight. Conversely, the day length is shortest around the winter solstice, which occurs on December 21st in the Northern Hemisphere and June 21st in the Southern Hemisphere. During the winter solstice, the North Pole is tilted away from the Sun, leading to the shortest period of daylight.

The day length also varies by latitude. Locations closer to the poles experience longer periods of daylight during the summer and shorter periods during the winter, while locations closer to the equator experience more consistent day lengths throughout the year. Additionally, the day length can be affected by weather conditions, such as clouds or fog, which can obscure the Sun and reduce the perceived day length.

Päivänpituus is an important factor in various fields, including agriculture, biology, and human health. Plants, for example, require specific day lengths to trigger flowering and seed production. In humans, the length of daylight can affect circadian rhythms, sleep patterns, and mood. Understanding päivänpituus is crucial for planning activities, such as outdoor work or recreation, and for studying the natural world.