Why do Satellite Navigation Systems work when it's cloudy?

I have a hiker's GPS (Garmin) which doesn't work when in forests or under cloud, presumably because it can't see its satellites. Why do Satellite Navigation Systems as used in cars work when it's cloudy? Do they not need to see their satellites?|||it uses a different wavelength from a satellite which is in a closer orbit to the earth, meaning the signal can penetrate through clouds. Think about this, AM radio is broadcast from one location in the country, and you can pick it up almost anywhere. This is because it has a longer wavelength and is able to "bend" around objects such as hills etc. Then think about FM radio, which has repeaters at slightly different frequencies every 30 miles or so. This is because it uses a shorter wavelength, which can't bend around objects. However you are able to receive a better quality signal. Mobile phones even shorter, masts are ever 3 miles or so. If memory serves me correctly sat navs use a short wavelength with a high intensity meaning they are able to penetrate the majority of weather conditions, where as your hikers GPS probably uses a longer one meaning it has difficulty.





Hope this goes someway to answering your question.|||remeber, the strains on a in car gps is more demanding due to traveling faster meaning it is more likely to go under clouds or behind tall buildings so it will require a better signal that a hiker gps

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|||Completely wrong answers.

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|||They do work in cloudy conditions. I find the worst thing for affecting their performance is tall buildings in city centres.





Maybe the car satnav has a more sophisticated antenna than the hikers' version.