The Beaufort scale is an empirical measure of wind strength, based primarily on observations of sea conditions and surface waves. It is now the standard for assessing wind speed and its effect on land and sea objects around the world. Let's consider this issue in more detail in the article.
Brief biography of Francis Beaufort
The inventor of the wind force scale, Francis Beaufort, was born in 1774. From an early age, he began to show interest in the sea and ships. Enlisting in the Royal Navy of Great Britain, he directed all his efforts to building a career as a sailor. As a result, Beaufort was able to achieve the rank of Admiral of the Royal Navy.
During his service, he not only performed military maritime tasks, but also devoted a lot of time to compiling geographical maps and conducting observations in various parts of the world. Beaufort served even in his old age. He died in 1857, when he was 83 years old.
The first scale for estimating wind speed
ScaleBeaufort was proposed in 1805. Up to this point, there was no specific standard by which to judge how weak or strong the wind was blowing. Many sailors based themselves on their subjective ideas.
Initially, the force of the wind on the Beaufort scale was presented as a graduation from 0 to 12. At the same time, each point spoke not about the speed of movement of air masses, but about how to behave in terms of controlling the ship. For example, when can sails be set and when they need to be removed to avoid breaking the masts. That is, the original Beaufort wind scale pursued purely practical purposes in maritime business.
This scale was adopted as the standard for the British Navy only in the late 1830s.
Using the scale on land
Beginning in the 1850s, the Beaufort scale began to be used for overland purposes. A mathematical formula was developed to convert her scores into the physical quantities used to measure wind speed, ie meters per second (m/s) and kilometers per second (km/s). In addition, manufactured anemometers (instruments that measure wind speed) have also begun to be calibrated to this scale.
At the beginning of the 20th century, meteorologist George Simpson added to the scale the effects produced by winds of the appropriate strength on land. Beginning in the 1920s, the scale began to be widely used around the world to describe wind-related phenomena, both at sea and on land.
Relationship between scale points and wind strength
As noted above, the force of the wind in points on the Beaufort scale can be converted into units convenient for use. The following formula is used for this: v=0.837B1.5 m/s, where v is the wind speed in meters per second, B is the value of the Beaufort scale. For example, for 4 points of the considered scale, which corresponds to the name "moderate breeze", the wind speed will be: v=0.83741.5=6.7 m/s or 24, 1 km/h.
It is often necessary to get the speed of air masses in kilometers per hour. For this purpose, another mathematical relationship was derived between the scale points and the corresponding physical quantity. The formula is: v=3B1, 5 ± B, where v is the speed at which the wind is blowing, expressed in km/h. Note that the "±" sign allows you to get speed limits that correspond to the specified score. So, in the example above, the wind speed on the Beaufort scale, which corresponds to 4 points, will be equal to: v=341, 5 ± 4=24 ± 4 km/h or 20-28 km/h.
As you can see from the example, both formulas give the same result, so they can be used to determine the wind speed in various units.
Further in the article we give a description of the consequences of the impact of the wind of one force or another on various natural objects and human structures. To this end, the entire Beaufort scale can be divided into three parts: 0-4 points, 5-8 points and 9-12 points.
Scores on a scale from 0 to 4
If the anemometer shows that the wind is inwithin 4 points of the scale under consideration, then they speak of a light breeze:
- Calm (0): The surface of the sea is smooth, without waves; the smoke from the fire rises vertically.
- Light breeze (1): small waves without foam on the sea; smoke indicates the direction the wind is blowing.
- Low breeze (2): transparent wave crests that are continuous; leaves begin to fall from the trees and the blades of windmills move.
- Light breeze (3): small waves, their crests begin to break; the leaves on the trees and the flags begin to waver.
- Moderate breeze (4): many "lambs" on the surface of the sea; papers and dust rise from the ground, tree tops begin to sway.
Scores on a scale from 5 to 8
These Beaufort winds cause a breeze to turn into a strong wind. They correspond to the following description:
- Fresh breeze (5): sea waves of medium size and length; small swaying of tree trunks, the appearance of ripples on the surface of lakes.
- Strong breeze (6): big waves begin to form, their crests continually break, sea foam forms; tree branches begin to sway, difficulty holding an open umbrella.
- Strong wind (7): the surface of the sea becomes extremely wavy and "voluminous", the foam is carried away by the wind; large trees move, and it is difficult for pedestrians to move against the wind.
- Strong wind (8): big waves that "break", the appearance of stripesfrom foam; the crowns of some trees begin to break, the movement of pedestrians is difficult, some vehicles move under the influence of the force of the wind.
Scores on a scale from 9 to 12
The last points of the Beaufort scale characterize the beginning of a storm and a hurricane. The consequences of such winds are given below:
- Very strong wind (9): very large waves with broken crests, reduced visibility; damage to trees, impossibility of normal movement of pedestrians and vehicles, some artificial structures are beginning to be damaged.
- Storm (10): thick waves, on the crests of which foam is visible, the color of the sea surface turns white; trees uprooted, damaging buildings.
- Severe storm (11): very large waves, the sea is completely white, visibility is very low; destruction of various nature everywhere, heavy rain, floods, flying people and other objects in the air.
- Hurricane (12): huge waves, white sea and zero visibility; the flight of people, vehicles, trees and parts of houses, widespread destruction, wind speeds of up to 120 km/h.
Scales describing hurricanes
Naturally, the question arises: are there winds that blow stronger than 120 km/h on our Earth? In other words, is there a scale that would describe the different strengths of hurricanes? The answer to this question is yes: yes, there is such a scale, and it is not the only one.
BFirst of all, it should be said that the Beaufort hurricane scale also exists, and it fits easily with the standard scale (points from 13 to 17 are added). This extended scale was developed in the middle of the last century, however, although it can be used to describe tropical hurricanes that often occur on the coasts of Southeast Asia (Taiwan, China), it is rarely used. There are other special scales for these purposes.
Detailed descriptions of hurricanes are given on the Saffir-Simpson scale. It was developed in 1969 by American engineer Herbert Saffir, then Simpson added flood effects to it. This scale divides all hurricanes into 5 levels based on wind speed. It covers all possible limits of this value: from 120 km / h to 250 km / h and more, and describes in detail the damage characteristic of a given score. The Saffir-Simpson scale is easily translated into the extended Beaufort scale. So, 1 point for the first will correspond to 13 points for the second, 2 points - 14 points and so on.
Other theoretical tools for classifying hurricanes are the Fujita scale and the TORRO scale. Both scales are used to describe a tornado or a tornado (a type of hurricane), while the first is based on the classification of damage from a tornado, while the second has a corresponding mathematical expression and is based on the wind speed in a tornado. Both scales are used around the world to describe the specified type of hurricane.
