§ 12. Image relief
Relative height. Known that the surface is uneven. On It is relatively level areas, hills, ravines, mountains. For the relief image on a plan or card, you must know the height increases and depth cuts the surface. To determine the height of terrain such as hill need to measure the vertical distance from its sole to the top. This can be done with leveling. Leveling- A simple device in the form of vertical rails with a height of 1 meter plummet and horizontal bar. The sequence of measuring the height of it (call it leveling) As follows: first set about leveling foot hill. According to plummet check whether strictly it stands upright. Horizontal plate leveling should be directed the slope. Along the fence "take aim" and pidmichayut point on a slope, in which she directed. There peg hammer. If leveling height is 1 m, this point will be at 1 m above the point where there is a leveling. Then transfer to the leveling peg and take aim at another point. The second point has to be higher at 2 m from sole. So consistently leveling hop several times along the slope. After going to the top, the number of stakes define the height in meters hill. So find out how many meters one point (in our example - the top hill) is higher relative to other points (foot hill). This height is called relative. With leveling can measure the height of the river above water, ravine slope above its bottom, and others.
Absolute height. If you take a close look at fig .., then see that the slope of a hill leveling asked four times. On the slope of other hand it fits five times. This means that with one sole side may be below, on the other - better. Because of this, and the relative height peaks, measured from different sides the hill may be unequal. To avoid DISCREPANCIES in altitude, the plans and location maps indicate no relative height and absolute height. Her vidlichuyut on a single level - from sea level, serving as a 0.
Aa - Excess point Earth's surface above sea level, serving as a 0 m. However, with different sea different level. From one of them to lead the countdown? In Ukraine and some other countries (Russia, Belarus, Moldova, etc.).. taken to keep counting the absolute height of surface points from the level Baltic Sea. To determine the absolute height of points, not necessarily go to him shores. In various places on the ground put special characters - rappers. They point to the height of the space above the Baltic Sea. From that mark, having spent leveling, You can determine the height of any point. For example, the absolute height Kyiv - 180 m
Plans and maps to be signed only absolute height. The absolute height of individual dots indicate location of dot. At her write the height in meters. This designation is called mark elevation.
Image terrain. Landforms on the plans and maps depicted horizontally. Horizontal- A line on the plan or map, connecting points of equal area absolute height. They outline the shape of the earth's surface irregularities. For Image hill marks the absolute height of transfer on the plan and connect lines. In terms of horizontal lines displayed brown. They are held at regular intervals height: for example, every 5 m, 10 m 50 m, 200 m and more. On-line horizontally may be signed by its altitude. Distance contour depends on the steepness of slopes. If the slope is steep, horizontally on the plan will be located close to each other if sloping - At greater distances.
Little dash, held perpendicular to horizontally, called berhshtryhy. They point the free end in which direction the slope decreases. Horizontal depicted on the plans not only increase but also depression. This berhshtryhy will be focused inside the free end circuit.
Questions and Tasks
1. What is the relative height difference of zero?
2. What does mark the height on the plan?
3. As depicted horizontally on the plan?
4. Determine how many meters in height held horizontally on the plan.
5. What is the relationship between slope steepness and distance contour?
6. What's different in terms of image height from depression?
7. Calculate the relative height of the hill when it altitude is 563 m and near horizontal foot - 310 m.