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Sunrise and Sunset table for San Jose, CA
The graph below shows sunrise and sunset times for San Jose. The shaded areas
show the time for civil twilight, nautical twilight and astronomical twilight.
For all practical purposes you should stop playing soccer outside within about
10min of sunset. The exact time when it gets too dark to play depends of course
on the date, exact position (close to the hills or under large trees it gets
darker earlier), ground (turf is less problematic than a grass field with lots
of holes) and current weather, so those numbers are just a general guideline
and commons sense should be applied.
Definitions
These definitions come from the Rise, Set and Twilight Definitions
web page.
Sunrise and sunset
Sunrise and sunset conventionally refer to the times when the upper edge
of the disk of the Sun is on the horizon, considered unobstructed relative to
the location of interest. Atmospheric conditions are assumed to be average, and
the location is in a level region on the Earth's surface.
Twilight
Before sunrise and again after sunset there are intervals of time, twilight, during which there is natural light provided by the upper atmosphere, which does receive direct sunlight and reflects part of it toward the Earth's surface. Some outdoor activities may be conducted without artificial illumination during these intervals, and it is useful to have some means to set limits beyond which a certain activity should be assisted by artificial lighting. The major determinants of the amount of natural light during twilight are the state of the atmosphere generally and local weather conditions in particular. Atmospheric conditions are best determined at the actual time and place of events. Nevertheless, it is possible to establish useful, though necessarily approximate, limits applicable to large classes of activities by considering only the position of the Sun below the local horizon. Reasonable and convenient definitions have evolved.
- Civil twilight
- is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished; at the beginning of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning before the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry on ordinary outdoor activities. Complete darkness, however, ends sometime prior to the beginning of morning civil twilight and begins sometime after the end of evening civil twilight.
- Nautical twilight
- is defined to begin in the morning, and to end in the evening, when the center of the sun is geometrically 12 degrees below the horizon. At the beginning or end of nautical twilight, under good atmospheric conditions and in the absence of other illumination, general outlines of ground objects may be distinguishable, but detailed outdoor operations are not possible, and the horizon is indistinct.
- Astronomical twilight
- is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 18 degrees below the horizon. Before the beginning of astronomical twilight in the morning and after the end of astronomical twilight in the evening the Sun does not contribute to sky illumination; for a considerable interval after the beginning of morning twilight and before the end of evening twilight, sky illumination is so faint that it is practically imperceptible.
Sunrise and Sunset in San Jose, CA for the next 12 month
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