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Location Location Location
A weather web-camera should be located with a clear and uninterrupted view of the
sky. However, how that view changes throughout the day and, over the whole year,
is an important consideration. Some questions to ask: Is one part of the sky more
active than others? Do more interesting clouds build a particular direction? Are
spectacular sunsets or sunrises more likely to occur in one season rather than another?
Does one direction have an appealing landscape to set the clouds against? A weather
web-camera location is often a compromise, so a number of candidate locations should
be given due consideration. A weather web-camera is not strictly restricted to just
one view all year round; so the web-camera could be redirected or even relocated
over the course of a year to capture the most favourable weather action.
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Sun awareness
It is essential to consider where the Sun is going to be in the web-camera's
frame. This is not just for artistic composition, but there are implications on
exposing a web-camera to excessive levels of light and heat. Sunlight beaming into
a web-camera's lens can degrade the performance of the imaging chip. A weather web-camera
is likely to be fixed onto one view 24-7, which means the Sun could remain
in frame for two to three hours at a time. Furthermore, as the seasons change, so
will the position and intensity of the Sun.
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Temperature and humidity
Ambient temperature and humidity have implications for a web-camera. The ambient
temperature range inside a typical home is from ten to thirty degrees centigrade
(50-86°F). On a window sill, this range expands from zero to forty degrees Celsius
(32-104°F). Add on a web-camera's own heat output of some twenty degrees Celsius
(68°F), and on a summer's day, a web-camera located on a window sill could easily
go outside of its operating temperature of around fifty degrees Celsius (122°F).
As a general rule, locations exposed to the Sun from midday through to mid-afternoon
should be avoided.
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Lenses
The interesting part of the sky can often occupy a significant proportion of the horizon. Which means for a weather web-camera trying to capture weather phenomena, a wide angle lens is most desirable.
Most IP cameras are designed for the surveillance of work stations, stairwells,
etc, and are supplied with lenses that are slightly wide angle. This equates
to roughly one eighth of the turn of a compass; for example, with a camera pointing
west, the edges of the frame will be inside the south western and north western
horizons. Desktop USB webcams have wider angle lenses because the subject (a person
sat at their PC) is only inches from the camera. These wide angle lenses cover a
lot of sky, for example from the south west to north west horizons, but the wide
angle lens may cause pin-cushion distortion which can make clouds look small
and the sky unnaturally curvy.
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Setting the scene
A well positioned web-camera respects the rules of composition. Exclude from the scene where possible, close-in distractions like street lights, cables, poles and aerials, as these may dominate the scene. In most urban environments some of these distractions are unavoidable. Buildings, rooftops and distant hills add a sense of perspective and depth to an image. Trees in frame will provide a sense of season, even when bare or covered in snow. Horizons should be horizontal; a wonky web camera makes it seem the web master neglected to straighten the camera after it was knocked awry! A web-camera scene that is pleasing to the eye will always bring repeat visits to a web-camera homepage.
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Revealing the sky
The sky always looks bigger when the scene includes a horizon; take away the horizon,
and the effect of perspective and therefore, the perception of the size of the sky
is lost. Typically, the landscape part should occupy between one fifth and one quarter
of the frame. For a landscape web-camera, this becomes one half to two thirds
of the frame.
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Filters
A landscape photographer will know a sky can be made a deeper shade of blue and
clouds made to stand out with the use of a polarising filter. However polarisers
are expensive and, given the tiny size of the filter required for most web-camera
lenses (no more than quarter of a square inch), a photographic grade multi-coated
filter is excessive. There are other sources of cheap polarising filters which include,
children's polarising sunglasses for £1($2) and, recommended, the linear
polarising filter strip that covers the LCD display in a redundant pocket
calculator. These can be attached in front of the lens using ingenious means
- tape.
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Legal Considerations
Some points to consider when locating a weather web-camera service:
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Summary
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