Wind is the horizontal component of the movement of air relative to the earth's surface. Occurs due to the appearance of a horizontal baric gradient. The wind is characterized by speed (strength) and direction. Speed is measured in m/s,km'h, i'3, strength - in conventional units - points. The direction is measured in degrees of the circular system of dividing the horizon or rhumbs. The direction of the wind is given a name (count) according to the point on the horizon from where the wind blows.
The wind arises under the action of the force of the pressure gradient, the force of friction, the deflecting force of the Earth's rotation and the centrifugal force. The friction force appears practically only up to a height of 500 m from the surface of the earth.
If we express the wind speed V in m/s and baric gradient G in mb at 60 soap, then
where φ is the latitude of the place.
The baric law of the wind. If you stand with your back to the wind, then in the northern hemisphere, low pressure is to the left, and high pressure is to the right of the direction of the wind. The opposite is true in the southern hemisphere.
Wind speed on the ship is determined by a hand-held anemometer. With the anemometer counter turned off, count and record the readings of the arrows on three dials (thousands, hundreds, tens and ones); stand on the windward side of the bridge, where the deckhouse and superstructure fencing do not distort the wind, raise the anemometer above your head to a vertical position with your right hand, and take a stopwatch ready for action in your left hand; when the hemispheres unwind, turn on the anemometer counter and start the stopwatch at the same time. After 100 sec, stop the anemometer counter, count a new indication of the arrows on all three anemometer dials. From the final count, subtract the initial and resulting difference divided by 100 (calculate the number of divisions in 1 sec); then, in the verification certificate, find the wind speed corresponding to this number of divisions.
Direction of the wind determined at anchor or drifting in the direction of the pennant, flag or smoke from the chimney with an accuracy of 5″. The wind is determined by the direction from which it blows, so 180″ must be added to the direction of the pennant (smoke).
rcjih the speed and direction of the wind are determined on the move of the ship, then I get! 'elements of the apparent or observable wind, which is the total vector of both the wind and the "wind" created by the movement of the ship - the course wind. The true wind is calculated using a wind calculator (CMO circle) or graphically on a maneuverable tablet or graph paper. The procedure for determining the elements of true evening with the help of a wind calculator is given on the reverse side of the SMO circle. On the maneuverable tablet e (Fig. '32.1, a) from the center of the tablet on the selected scale, plot the inverse velocity vector of the ship - in i / sec and the apparent wind speed vector W in m/sec. Connect the end of the vector - with the end of the vector - we get the true wind vector . The magnitude of the vector intend
compass on the selected scale, determine the direction on the outer scale of the tablet, moving the vector in parallel to the center of the tablet.
On graph paper, draw a line of the true meridian (Fig. 32.1, b) and from an arbitrary point on this line on the selected scale, plot the inverse velocity vector of the ship - in m/s and the apparent wind vector on the same scale. The vector will be the true wind vector; its direction will be from the end of the course wind vector to the end of the apparent wind vector. With such constructions, we get the direction where the wind blows, so 180 ° must be added to the resulting direction.
The anemorumb'ometer measures the average values of the speed and direction of the true wind.
The daily course of the wind. The wind speed increases in the morning, By evening it weakens. In mid-latitudes, this change is of the order of 3-5 m/sec. In summer, the daily course of wind speed is greater than in winter, and on clear days it is greater than on cloudy ones. Over the ocean, the daily course of the wind is almost imperceptible.
Due to the heterogeneity of heating of various zones of the earth's container, there is a system of atmospheric currents on a large planetary scale (the general circulation of the atmosphere).
P a saty - winds blowing all year round in one direction in the zone from the equator to 35 ° N. sh. and up to 30 ° S sh. Stable in direction: in the northern hemisphere - northeast, in the south - southeast. Speed - up to 6 m/sec. Vertical power average up to 4 km from sea level.
Monsoons are winds of temperate latitudes that blow from the ocean to the mainland in summer and from the mainland to the ocean in winter. Reach speed 20 m/sec. Monsoons bring dry, clear and cold weather to the coast in winter, cloudy in summer, with rain and fog.
Breezes are caused by uneven heating of water and land during the day. At 9-10 h there is a wind from the sea to land (sea breeze). Night 1, o from the chilled coast (high pressure) - to the sea (coastal breeze). Wind speed with sea breezes up to 10 m/s, at coastal - up to 5 m/sec. Breezes are observed on the shores of the Baltic, Black, Azov, Caspian and other seas. As the distance to the sea, the strength (velocity) of the breeze noticeably weakens, but under favorable conditions it can be observed up to 100 miles from the shore.
Local winds arise in certain areas due to the features of the relief and differ sharply from the general air flow: they arise as a result of uneven heating (cooling) of the underlying surface. Detailed information about local winds is given in sailing directions and hydrometeorological descriptions.
Bora is a strong and gusty wind that blows down a mountainside. Brings a significant chill. It is observed in areas where a low mountain range borders the sea, during periods when atmospheric pressure increases over land and the temperature drops compared to pressure and temperature over the sea. In the area of Novorossiysk Bay, boron (Novorossiysk north-east) operates in November - March - on average about 50 days a year - with average wind speeds of about 20 m/s(individual gusts can be 50-60 m/s). The duration of action is from one to three days. A sign of the appearance of bora in this area is a cloud descending from the Markhotsky pass. Similar winds are observed on Novaya Zemlya (“mountainous” or “vetok”), on the Mediterranean coast of France (“mistral”) and off the northern shores of the Adriatic Sea.
Sirocco - hot and humid wind of the central Mediterranean; accompanied by cloudiness and precipitation.
Baku Nord - a strong cold and dry north wind, reaching speeds up to 20, and sometimes 40 m/sec. It is observed in the Baku region both in summer and in winter.
Norder is a northerly or northwesterly wind blowing in the Gulf of Mexico.
Bayamos - a strong squally wind with rain and a thunderstorm off the southern coast of Cuba.
Tornadoes are whirlwinds over the sea with a diameter of up to several tens of meters, consisting of water spray. They exist up to a quarter of a day and move at a speed of up to 30 uz. The wind speed inside the tornado can reach up to 100 m/sec. Occur most often in low latitudes; l temperate latitudes may occur in summer.
Ballistic (reduced) wind - the calculated wind, which is assumed to be constant in speed and direction within a given thickness of the atmosphere and in its action is equivalent to the total effect on the projectile (rocket) of all real winds in this thickness.
Ballistic wind calculation:
Based on balloon observations, determine the actual wind at different heights:
The speed and direction of the wind in different layers are calculated using an aerometeorological tablet (AMP) or, as it is called, the Molchanov circle. The order of work on this tablet is always attached to it.
