Definition and types of height
First of all, height is called distance of any geographic point according to her plumb line from accepted reference level. The very value of the height of a point is called its "mark".
But the definition of height is not as interesting as its types. It is known that there are only two types of heights: absolute and relative. And in order to understand their differences, you should consider each of them in more detail.
About absolute altitude
She is also called altitude, absolute mark and height above sea level. The peculiarity of this height is that it is measured from mean ocean level(often the sea).
The absolute height is positive and negative. In the first case, the terrain lies above the ocean level, in the second - below. Most of the land has a positive absolute height. But the negative is somewhat less common. Examples are lands such as:
- Death Valley that in North America (almost -85 meters);
- Qattara depression in Africa (ca. - 132 meters);
- and Dead Sea coast(already -417.5 meters).
Moreover, the last example is the most low-lying piece of land in the whole world.
About relative height
But the relative height is always measured from conditional level, which is taken as zero. In other words, if the absolute height is considered from the ocean level, then the conditional one is from any other level. For example, the height of a person can be compared to the height tree, the mountains or another arbitrary object.
Relative height also shows excess level one point on the earth's surface above another (as far as it is higher or lower).
In general, both absolute and relative heights are used mainly for relief characteristics.
It is noteworthy that height is sometimes measured tangent to center of the earth. But this happens very rarely due to distortion when polar compression.
The surface of our planet is uneven: some of its parts are higher, others are lower; there are high mountains, deep depressions, vast plains. The irregularities of the earth's surface are called. How to show relief on paper? Obviously, first of all, it is necessary to measure the height of the hills and the depth of the depressions.
Relative height
A small height can be measured using a level device. You can make a simple level yourself. It is a wooden block 1 m long with a transverse bar attached to its end. A nail is driven into the middle of the bar and a plumb line is tied to it - a thin but strong thread with a small load, by which it can be judged whether the level is installed vertically or obliquely. To measure, for example, the height of a hill, the leveler sets the level at its sole strictly vertically, along a plumb line. The horizontal bar of the level should be directed towards the slope of the hill. Looking along the bar, the leveler notices where it is directed. At this point, the assistant leveler drives in the first peg. Since the height of the level is 1 m, the driven peg is 1 m above the place where the level is installed. Then the leveler moves the level to the place of the first peg and indicates to the assistant where to drive the second peg.
Points - this is the excess of this point on the earth's surface over another along a plumb line.
Altitude
The figure shows a hill, the sole of which is higher on one side than on the other. Consequently, the relative height of the top of this hill is not the same on its different sides. The top of a hill can have several relative heights. How to show this on the map? To avoid confusion, scientists agreed to count all heights and depths from some constant level - the average sea (ocean) level, taken as 0. The height measured from this level is always the same.
The absolute height of a point is the excess of this point on the earth's surface along a plumb line above sea level.
True, there are difficulties as to which level to take for middle level seas: in different seas and oceans, along different coasts, the water level is not the same (due to currents, the shape of the coasts, the rotation of the Earth, etc.). In Russia, the absolute heights of all points are measured from the level near Kronstadt. Other countries have their own reference points for absolute heights.
Horizontals (isohypses)
To indicate on the map not only the height of individual points on the earth's surface, but also to depict entire spaces that have a convex or concave shape, special lines are used.
For clarity, imagine that a hill during a flood is flooded with rising water. The rise of water occurs gradually, and different levels of standing water can be drawn on the surface of the hill. When looking at the hill from above, the water levels will look like closed and, as it were, nested curves. These are the horizontals.
We remember: What objects in the classroom have a horizontal surface? Where in nature have you seen a horizontal surface? Which lines in your class are vertical?
Keywords:absolute height, relative height, level.
1. Relative height. As you know, the earth's surface is very uneven. On it there are flat areas, hills, ravines, mountains. In order to depict the surface of the terrain on a plan, it is necessary to measure the height of the hills, the depth of the ravines. There are relative and absolute heights of the terrain (Fig. 29)
Fig 29. Absolute (1) and relative (2) height of the terrain.
Relative height shows how much one point on the earth's surface is higher than another. A level is used to determine the relative height. A simple level is easy to make yourself (Fig. 30).
Figure 29. Homemade level.
A plumb line is fixed on its vertical bar. On it you can check whether the level is installed correctly.
To determine with the help of a level, for example, how much the top of a hill exceeds its sole, one proceeds as follows. Install the tool at the bottom of the hill. One of the students, holding the level in a vertical position, sights (“aims”) towards the hill. Then he mentally draws a horizontal line from the level to the hillside and notices the place where he "aimed". Another student drives a peg into this point. Now the level must be moved to the place where the peg was driven in. If the height of the level is 1 m, then the point where the peg is driven in will be 1 m higher than the place where the level stands (Fig. 31). So, having passed the entire slope, it is not difficult to calculate the relative height of the hill.
Figure 31. Determining the relative height of a hill.
2. Absolute height. The surface of the Earth in different parts rises to different heights above sea level. The height of a point above ocean (or sea) level is called a b solute height. The absolute height in Belarus is calculated from the level of the Baltic Sea, which is taken as 0 m height.
*There are points on the territory of Belarus, the absolute height of which has already been determined. At these points there are special signs where the absolute height is recorded. If it is necessary to find the absolute height of another point that is close to this sign, then it is measured using these data.
1. What is the level used for? 2. What is the difference between relative height and absolute height? 3* What does the elevation mark show?
Practical work:
1. Determine the absolute height of the hill in fig. 32. Tell us how to calculate the relative heights of a hill, knowing its absolute height.
Fig 32. The relative height of the hill (light arrows) and its absolute height (black arrow); determine their size.
2. Measure the relative height of a hill during a field trip
&eleven. Relief image by contour lines
We remember: What is a horizon? What forms of irregularities in the surface of the Earth do you know?
Keywords: relief, absolute and relative heights, contour lines.
1. Contours. In addition to local objects, the plans and topographic maps depict the irregularities of any part of the terrain. A set of irregularities in the earth's surface is called r e l e f o m. The relief on the plans and physical maps is depicted by horizontal lines. H o r i z o n t a l- these are lines on a plan or map that connect points in the area that have the same height above sea level (What is this height called?)
2. The image of the hill with contour lines. In order to depict a hill on a plan or topographic map using contour lines, you need to go with a level from west to east through the top of the hill and, starting from the water level in the sea, drive pegs into points that are 1 m, 2 m above the water level in the sea etc. Then do the same from north to south. The position of the driven pegs is applied to the plan and then, with a smooth line, first connect all points with an absolute height of 1m, then 2m, etc. We get the image on the plan of the hill with contour lines.
Rice. 33. Image of a hill with contour lines. Which slope of the hill is more gentle - western or eastern?
The heights of the contour lines are indicated by numbers. Contours are drawn through an equal number of meters. The shape and location of contour lines allow you to imagine and read the terrain. For example, if the contours are close to each other, then the slope is steep; if at a great distance from each other - the slope is gentle.
(Fig. 33). The direction in which the slope descends is depicted by small dashes (berghatches) drawn perpendicular to the contours. Depressions are also depicted by horizontals (Fig. 34) (where are the berghashes directed on the horizontals depicting depressions?). Sheer ledges, cliffs are depicted on the plan with small strokes.
Rice. 34. Image of the basin on the terrain plan. How is this image different from the image of a hill?
One of the quantities characterizing the location of an object in space is the height. It shows the vertical distance from the given level to the desired point. Consider two parameters of the mentioned value, or rather, find out how the absolute height differs from the relative one.
Definition
Absolute called the height, expressing the distance from sea level to the object of interest.
Relative height is the coordinate associated with any chosen datum, except for sea level.
Comparison
Thus, the difference between absolute height and relative height lies in what is taken as the starting point. In the first case, the horizontal plane of the sea, which is in a calm state, acts as a reference point. Moreover, if the object is placed above this level, then the value of the absolute height is positive, and if it is located below the mentioned surface, this indicator will be negative.
It is the absolute height of mountains, flat areas and other components of the relief that is noted on plans and maps. This ensures maximum consistency of values. However, sea levels are not the same everywhere. Therefore, scientists agree on which surface should be taken as zero.
So, in Russia and neighboring countries, when measuring the height of objects, they are repelled from the level corresponding to the Baltic Sea. For convenience, even very far from these water places, special signs are fixed, on which their absolute coordinates are indicated. Using these references, you can find the vertical distance from the reference sea level to any required point.
Considering what is the difference between absolute and relative height, we should dwell on the second of them. Here the starting point is arbitrarily chosen. For example, you can calculate the height of a hill relative to its foot. At the same time, there is a possibility that the indicators taken from different sides of the natural object will not match. Relative altitude, showing the distance between closely spaced points, is often a more important characteristic from a practical standpoint than absolute altitude, associated with a distant sea.
The tool used to determine the height is a level. Its simplest version is a meter rail, to the top of which a short bar with a plumb line is perpendicularly attached. The last component allows you to install the level strictly vertically. When measuring the height, for example, of the same hill, the device is placed at its sole. Having deployed a short bar towards the slope, they “aim” with it, that is, they mentally draw a line that continues this horizontal line.
The end point (it is at a height of one meter from the foot) becomes the next support for the level. All actions are repeated, and after reaching the top of the object, calculations are made relative to the total height of the hill.
Relative height
On the concept of relative height. Vertical bidirectional arrows indicate the relative height of one hill relative to any other
Relative height - topographic elevation any point on the earth's surface relative to another point, measured vertically, equal to the difference in the absolute heights of these points (for example, the height of a mountain peak above the bottom of the nearest valley); the vertical distance from the specified source level to the level, point, or object taken as a point.
The higher peak through the base of the saddle is often directly adjacent to the lower peak, but this is not always true in the case of sufficiently deep saddles. Such cases can only be identified through careful analysis of geographic information. For example:
If the base of a saddle of a mountain is close enough to the peak of that same mountain, the relative height calculation is not particularly difficult and can be done manually using a topographic map.
In more complex cases, such as those described above, a computer is usually used. The USGS uses a special WinProm program written by Edward Earl.
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See what "Relative Height" is in other dictionaries:
relative height- (T/Wp) Dimensionless value equal to the ratio of the height to the initial width. Note Approximately the relative height of the four types of V-belts is as follows: 0.9 - narrow belt; 0.7 - normal belt; 0.5 - broadened ... ...
Excess (a. relative altitude, relative height; n. relative Hohe; f. altitude relative; and. altura relative), difference abs. heights k. l. points on the earth's surface relative to other points (for example, the height of a mountain peak above the level of the nearest ... ... Geological Encyclopedia
Excess, the difference in absolute heights of any point on the earth's surface relative to another point ... Big Encyclopedic Dictionary
relative height- Difference of absolute heights of two points. Syn.: excess ... Geography Dictionary
Excess, the difference in absolute heights of any point on the earth's surface relative to another point. * * * RELATIVE HEIGHT RELATIVE HEIGHT, excess, difference in absolute heights (see ABSOLUTE HEIGHT) of any point on the earth ... ... encyclopedic Dictionary
Relative height- the height of the terrain point, calculated not from sea level, but from some arbitrarily chosen level surface. Sometimes O. in. called the excess of one point over another. For example, the excess of the top of a hill above its sole is called O ... Brief dictionary of operational-tactical and general military terms
The excess of any point on the earth's surface relative to another point, equal to the difference in the absolute heights of these points (for example, the height of a mountain peak above the bottom level of the nearest must) ... Great Soviet Encyclopedia
Exceeding, the difference in absolute heights of k. l. points on the earth's surface relative to other points ... Natural science. encyclopedic Dictionary
Relative height of the compressed zone of concrete- - the ratio of the height of the compressed zone of concrete to the working height of the section. [Terminological dictionary for concrete and reinforced concrete. Federal State Unitary Enterprise "Research Center" Construction "NIIZHB them. A. A. Gvozdeva, Moscow, 2007, 110 pages] Heading term: Properties of concrete Headings ... ... Encyclopedia of terms, definitions and explanations of building materials
decision altitude (DA) or decision height (DH)- Set altitude or height on a precision approach or approach with vertical guidance at which an aborted approach (go-around) should be initiated if not set ... ... Technical Translator's Handbook
