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Written by David H. Johnston
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Sunday, 18 February 2007 04:08 |
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 Global Positioning System satellites transmit
signals to equipment on the ground. GPS receivers passively receive satellite signals;
they do not transmit. GPS receivers require an unobstructed view of the sky, so they are
used only outdoors and they often do not perform well within forested areas or near tall
buildings. GPS operations depend on a very accurate time reference, which is provided by
atomic clocks at the U.S. Naval Observatory. Each GPS satellite has atomic clocks on
board.
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Written by David H. Johnston
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Saturday, 13 January 2007 18:57 |
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 Dear Weather Guy,
How do barometers work? Why do meteorologists use barometers? What do barometers do? When were barometers first invented? How do you make a model of a barometer? How accurate are barometers?
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Written by David H. Johnston
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Friday, 13 October 2006 17:06 |
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We recently
found this article with a fantastic animation clearly showing the difference
between spring and neep tides.
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Written by David H. Johnston
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Wednesday, 20 September 2006 18:21 |
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 Gel-coat is the material which is used to create the glossy colored finish
on the hull and deck. It is also the first material that is applied to
the form, when building the kayak. Apart from generating the beautiful
glossy finish on the kayak, the gel-coat’s function is to protect the
fiberglass laminate - the boat’s main material – from moisture.
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