Length of Day

(redirected from Day length)
Also found in: Wikipedia.

Length of Day

 

the interval of time between sunrise and sunset, during which the sun is above the horizon. The length of day depends upon the geographic latitude of a place and upon the inclination of the sun. At the equator, the length of day is constant and equals 12 hours. In the northern hemisphere, the length of day is more than 12 hours during the positive inclination of the sun (that is, in the spring and summer) and less than 12 hours during the negative inclination of the sun (in the autumn and winter). At the equinoxes (spring and autumn), the day equals the night (if one does not consider refraction) everywhere on the earth. The longest day is the summer solstice and the shortest is the winter solstice. Within the polar circles, the length of day in the summer can exceed 24 hours (the polar day), and at the poles daytime lasts six months.

References in periodicals archive ?
The production of most fruiting vegetables such as tomatoes and cucumbers depends more on maturity of the plants than day length. They're sometimes referred to as day-neutral.
Previous calculations for the day length fell between 10 hours, 36 minutes and 10 hours, 48 minutes, but scientists could not give an exact number.
The findings suggest that using light treatment in the late third trimester when seasonal day length is shortening could minimize postpartum depressive symptoms in high-risk mothers during the first three months of their children's lives.
The researchers found that the link between higher serum vitamin D levels and lower plasma cholesterol levels was independent of body adiposity, dietary factors, physical activity, parental education, and day length prior to blood sampling, Medical Xpress reported.
While the research did not indicate precisely when and where these future earthquakes will occur, it showed that most of the intense earthquakes that responded to changes in day length seemed to occur near the equator.
For the proposed research, accurate control of light intensity ( 0 to 1,000 mol(PAR)), far red/red ratio, day length, temperature (-10 to 45C), relative humidity (40 to 85 %), carbon dioxide level (0 to 2,000 ppm) and airflow is needed.
We tested using general linear models (GLM) with IBM SPSS Statistics 22 if 1) age of birds, 2) sex, 3) breeding method and 4) day length influenced daily ranges, distance travelled per hour and number of times capercaillies fed per h.
Birds such as blackbirds and blue tits are behaving much as normal, as day length is an important factor in when they breed, while sightings of insects including ladybirds and redtailed bumblebees are also around average.
"But long-distance migratory birds, for example, time their migration based on day length in their winter range.
Some edible plants are referred to as "day-length sensitive," although day length is a misnomer because these plants are actually sensitive to the number of hours of darkness.
The days are longer (day length reached 14 hours today), the sun is stronger and general conditions are such that a prime-growing season is upon us.