The Zambretti Forecaster is an instrument, which allows you to make forecasts of weather instantly, for a radius of about 50 km of your location. Devised from the Negretti & Zambra firm at 1915 (Patent Nr 6276) and based on actual experiences and results obtained over a period of years. Designed for the Northern Hemisphere and especially for the UK, is in fact a handy computer, using easily observed weather factors, programmed to yield concise forecasts based on the variations of input data. With the Zambretti Forecaster and correct observations of a barometer, you can make precise and up to the minute more than 90% accurate forecasts at your location. The most accurate results are when the forecasts are made at 09:00 local time. Has been sucessfully tested by NATO Special Operations Forces, on exercises under extreme conditions in the Cairngorms mountain range, in the eastern Highlands of Scotland and in the Arctic. |
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The Zambretti Forecaster is based, like the Sager Weathercaster, on the Buys Ballot's law. This law may be expressed as follows. In the Northern Hemisphere, if a person stands with his back to the wind, the low pressure area will be on his left from 90° to 135°. This is because wind travels counterclockwise around low pressure zones in the Northern Hemisphere. It is approximately true in the higher latitudes of the Northern Hemisphere, and is reversed in the Southern Hemisphere, but this angle is not a right angle in low latitudes. |
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The Zambretti Forecaster consists of 3 plastic (original version from ivorine) discs of descending radius, arranged concentrically and secured together by means of a rivet. There is also a hole (current version) for a hanging cord. |
Disc 1: Wind direction
Disc 1 (back side): A circular list with 26 letters followed by the forecasts
Disc 2: Barometric pressure in inches of mercury and millibars
Also the index for wind direction
Disc 3: 3 windows for the selection of a letter based upon pressure trend in Winter or Summer
Also the index for Barometric pressure |
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In the instrument image above we have for the wind, calm, for the pressure, 29.53 inHg and 1000 millibars or hPa and for the pressure trend, steady. These settings translate to the letter N which, when looked up in the back side, results in the following forecast. Showery, bright intervals. |
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Note: In 1850, Henry Negretti (1818-1879) and Joseph Zambra (1822-1897) established a partnership in London, as optical and scientific instrument makers and photographers. They were appointed optical instrument makers to Prince Albert, to the Royal Observatory, Greenwich and to the British Admiralty. In 1853, when the Crystal Palace (a cast iron and plate glass building, originally erected in Hyde Park in London, to house the Great Exhibition of the Works of Industry of all Nations, at 1851) was re-erected in Sydenham, Negretti and Zambra became the official photographers of the Crystal Palace Company, receiving the right to photograph and produce stereoviews of the new building. In 1856, Negretti and Zambra financed Francis Frith's photographic trip to Egypt, Nubia and Ethiopia, and from 1857 to 1860, the company produced over 500 stereoviews of Frith's voyage. In 1863, Henry Negretti was the first photographer to take aerial photographs of London from a balloon. The Negretti & Zambra firm has more than 100 years history and is well known for her excellent quality products.
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Weather Predictions
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A: Settled fine
B: Fine weather
C: Becoming fine
D: Fine, becoming less settled
E: Fine, possibly showers
F: Fairly fine, improving
G: Fairly fine, possibly showers early
H: Fairly fine, showery later
I: Showery early, improving
J: Changeable, mending
K: Fairly fine, showers likely
L: Rather unsettled, clearing later
M: Unsettled, probably improving
N: Showery, bright intervals
O: Showery, becoming more unsettled
P: Changeable, some rain
Q: Unsettled, short fine intervals
R: Unsettled, rain later
S: Unsettled, rain at times
T: Very unsettled, finer at times
U: Rain at times, worse later
V: Rain at times, becoming very unsettled
W: Rain at frequent intervals
X: Very unsettled, rain
Y: Stormy, possibly improving
Z: Stormy, much rain |
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Zambretti Forecaster Versions
(Several versions from 1915 to 1930)
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The use of a Zambretti Forecaster may seem antiquated today, since we have a variety of weather informations and forecasts, straightly, through various means of communication and systems. But in cases where several incidents silence this informations, its existence can be lifesaving. Imagine a sailing boat in the middle of the sea with serious damage on electrical equipment and poor reception even in the possible emergency radio, trying to carve out a safe route amid intense weather. It can only rely on experience and in anything non-electronic available. Because as the experience says... System that not exists, doesn't spoil! |
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Personal Weather Station at Kato Pylea
Thursday 21-11-2024
This data is not to be used for protection of life and property 
