O Breva Génie 01 é uma estação meteorológica de pulso, inteiramente mecânica - indica as horas e tem altímetro, barómetro - para previsão do tempo - e indicador de reserva de corda (65 horas de autonomia). O calibre, automático, foi desenvolvido em exclusivo para a Breva por Jean-François Mojon/Chronode.
O nome "Breva" inspira-se em "La Breva", um vento quente, vindo do sul, que contribui para o microclima ameno em redor do Lado de Como, no norte de Itália.
Com caixa de 44,7 mm, o Génie 01 é uma edição limitada de 55 peças de ouro branco e 55 de ouro rosa.
Da marca:
The anaerobic barometer and altimeter in the Génie 01
A barometer is an instrument for measuring air pressure, first invented by Evangelista Toricelli, a pupil of Galileo, in 1643. There are two main types of barometer: a mercury barometer, in which the pressure of the air forces a small column of mercury up a tube (similar to a mercury thermometer); and the anaerobic barometer, in which one or more aneroid capsules (aneroid means ‘without air’) expand/contract with changing air pressure.
The barometer and altimeter (air pressure changes with both altitude and weather conditions) measure air pressure with two small aneroid capsules stacked one above the other – the top one being clearly visible on the dial side at 5 o’clock.
The aneroid capsules in the Génie 01 were especially developed to Breva's specifications to optimise their precision and use in a wristwatch. The capsules are made from a special non-magnetic memory-metal (Breva patented invention), which is lighter and stronger than aluminium and has twice the ductility of steel. The capsules are exposed for long durations to high temperature and pure oxygen to maximise thermal conductivity and oxidation resistance. A clearly visible lever rests on top of the aneroid capsules and transmits the combined height of the capsules through a complex system of gears and racks to the altimeter indication and the barometer. The gearing for these two displays has been carefully calculated as the scale of changing air pressure due to altitude variations is quite different to weather variations.
The attitude display reads from -300 to +5,300 metres, while the barometric display ranges between 973 and 1053 hectopascals (hPa). In a nod to the original method of measuring air pressure in inches of Mercury, an inner scale of the barometer is marked mmHg: Hg being the atomic name for Mercury (Hg from the Greek hydrargyrum meaning ‘silver water’).
The Génie 01 barometer
Before using or adjusting the barometer, air pressure inside the movement should be equalised with the exterior air pressure using the valve at 4 o’clock. What is important in using air pressure to forecast the weather is the recent change in pressure, rather than the pressure itself. Rising pressure indicates good weather coming, falling pressure is a sign of inclement weather ahead.
The faster the pressure changes and/or the larger the change, the more extreme – good or bad – the coming weather is likely to be. After equalising the interior air pressure, the barometer dial is rotated so that the hand points through the centre of ‘météo’ (French for weather forecast) to 1013 hPa, which is the standard (not necessarily actual) air pressure at sea level. Over the next hours – assuming no change in altitude – the hand might remain in place, indicating no change; move toward lower pressure, suggesting a possible deterioration in the weather; or move towards higher pressure, suggesting sunny weather coming on its way. Slow/small movement suggests minor changes, while fast and/or large movement forecasts more extreme weather ahead.
The Génie 01 altimeter
Before using or adjusting the 5,300m/17,000' altimeter, air pressure inside the movement should be equalised with the exterior air pressure valve at 4 o’clock. Because air pressure can vary throughout the day (due to weather changes) the altimeter should be regularly set at a known altitude to ensure accurate results. As the hand is directly linked to the air pressure, the pusher at 2 o’clock moves the altitude dial (rather than the hand) left or right to synchronise the correct altitude with the indicator hand.
Air pressure and weather forecasting
Air pressure is caused by the gases in the atmosphere – mainly nitrogen (N2) and oxygen (O2) – pushing in all directions (think of gas in a balloon). These gases may be relatively light, but there are a lot of them in the atmosphere stretching approximately 24 kilometres (15 miles) above our heads. Air density/pressure varies due to: temperature – hotter air is less dense so floats above cool air; altitude: the closer air is to the planet’s surface – the more gravity packs its molecules together so increases its density; and humidity. Why clouds float Paradoxically water vapour molecules H2O – two hydrogen (lightest matter in the universe) plus one oxygen – are actually lighter than air molecules, which are approximately 80% N2 (two nitrogen atoms) and 20% O2 (two oxygen atoms). That’s one – though not the only one – of the reasons clouds float! Note that liquid water is much heavier than water vapour, which is why it rains.
Winds
Because of the earth’s rotation, angle, sun striking half the surface, oceans and ice caps, the air temperature – and air pressure – varies throughout the day, the seasons and the years. These variations cause colder and hotter regions in the atmosphere. Colder regions are denser than warmer regions so have higher pressure. High pressure moves towards low pressure (prick a balloon and the gas rushes out, not in) causing wind. Wind moving from high pressure to low pressure are between a rock (earth’s surface) and a hard (high-pressure) place, so there is nowhere for all that incoming air to go. Nowhere to go… except UP!
Extreme weather
When the air pressure drops very low, massive amounts of air are forced upwards so fast that they spin to form whirlwinds, tornadoes, cyclones and hurricanes. Note that cyclones and hurricanes are similar phenomenon but spin in different directions due to the Coriolis effect: cyclones rotate anti-clockwise in the southern hemisphere, hurricanes clockwise in the north.
Water spinning down the plug
However, while the Coriolis effect influences light air over thousands of kilometres, despite widespread belief it is far too weak to influence the direction small amounts of relatively heavy water spin down the plughole. That’s just an urban myth! Come rain or hail So in areas of relatively low pressure, air generally rises up. And as it rises, the air cools and the molecules of water it contains condense into water vapour that eventually forms white fluffy clouds. However, if the air pressure is low enough, the winds will be stronger so the incoming air will rise even higher where the lower temperature of the air can no longer support the ever denser water molecules, so they precipitate into rain, snow or even freeze as hail. Changes But predicting the weather isn’t quite that simple because it isn’t the actual air pressure that forecasts the weather – knowing the air pressure just tells you what you can learn by looking out the window, i.e. what the weather is now, not what’s coming. It is the change in air pressure that indicates what weather is coming, rather than the actual pressure itself.
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