Knowledge points of geographical isoline in college entrance examination

An isoline is a line connecting points with equal exponential values. Isogram is a set of isolines on the map to represent the continuous distribution of geographical phenomena on the ground and in space, as well as the phenomenon of uniform gradual change. Let's share with you some knowledge of the geographical isoline of the college entrance examination, hoping to help you. Welcome to read!

Knowledge of geographical isoline in college entrance examination 1

* * * The same features of isolines:

(1) collinear equivalence;

(2) The same figure is equidistant, that is, the values of two adjacent isolines are equal or the numerical difference is equal;

③ Any two isolines in the same drawing generally do not intersect (except steep cliffs);

④ Isograms are generally closed curves, but they may not be closed in local maps;

⑤ The denser the isoline, the greater the difference of unit horizontal distance, and the thinner the isoline, the smaller the difference of unit horizontal distance;

⑥ The straightness of isoline indicates that there are fewer factors affecting this area and its adjacent areas, while the curvature of isoline indicates that there are more factors affecting this geographical thing.

Interpretation method of isoline map;

1. Look at the name of the picture and the contour map of things.

—— Identify what geographical things are reflected by isolines;

2. Explain the density of isoline arrangement

—— The density of isoline represents the magnitude of numerical change;

3. Read out the numerical value, maximum value, minimum value, gradual change law and causes.

The key to solve the problem is to find out the law of isoline change and analyze its reasons;

4. The trend of isoline can judge the main influencing factors.

-Interpret and explain the reasons in combination with relevant geographical knowledge;

5. The values of two adjacent isolines can only be the same or the same distance apart;

6. Judging the bending direction of isoline by "convex low is high, convex high is low"

Interpretation of contour map

The height annotation of contour map is "altitude" (that is, the vertical distance of altitude at a certain point. The altitude of China refers to the distance above the sea level of the Yellow Sea).

1. Value size

The numerical value between two contour lines is read according to the law of "greater than decimal, less than large number", and the numerical value inside the closed curve between two contour lines follows the law of "greater than large number, less than decimal".

2. Density

On the same map, the denser the contour lines, the steeper the ground slope; The thinner the contour, the slower the slope. Comprehensive comparison should use "relative height/horizontal distance". The greater the ratio, the steeper the slope.

3. Shape characteristics

① Judging the terrain: below 200 meters above sea level, the contour lines are sparse, broad and flat-plain terrain; Below 500 meters above sea level, the relative height is less than 100 meters, the contour lines are sparse, and the curved part is gentle-hilly terrain; Above 500 meters above sea level, the relative height is above 100 meters, the contour lines are dense, and the valley turns into V-shaped mountain terrain; High altitude, more than 500 meters, relatively small height. Contour lines are very dense at the edge, and the terrain at the top plateau is obviously sparse.

(2) judging the surface morphology; The contour line is closed, and the value decreases gradually from the center to the surrounding mountains; On the contrary, the value gradually increases from the center to the periphery-basin or depression; The lowland between the two mountains looks like a saddle. The curved part of the contour line protrudes to the lower part-ridge (also called watershed), and the maximum curvature-the connection line of the ridge line (also called watershed); The contour line protrudes from the lower part to the higher part-valley, and the connecting line at the maximum bend of the contour line-valley line (also called catchment line); Intersection of contour lines-steep cliff.

③ Judging the direction of slope: slope indicator line-a short line perpendicular to the contour line and pointing to the side with decreasing slope; Sunny slope-the slope faces low latitude; Shaded slope-the slope faces high latitude; Upwind slope-warm and humid air flow rises along the slope; Leeward slope-warm and humid airflow sinks along the hillside.

Knowledge of geographical isoline in college entrance examination II

1. Determine the terrain according to the numerical size and distribution characteristics of contour lines.

Below 200 meters above sea level, the contour lines are sparse, and the vast and flat terrain is plain; Below 500 meters above sea level, the relative height is less than 100 meters, the contour lines are sparse, and the curved part is gentle hilly terrain; Above 500 meters above sea level, the relative height is above 100 meters, the contour lines are dense, and the valley turns into V-shaped mountain terrain; The altitude is high, the relative height is small, the contour edges are very dense, and the top is obviously sparse like a plateau; A basin with a small central contour and a large peripheral contour.

2. Judge the name of the local terrain.

The peak of the contour line is closed and the center of the contour line is obviously higher than the surrounding area. The part between the two peaks is a saddle, the part where the contour line bends upward is a valley (lower left), the part where the contour line bends downward is a ridge (lower right), and the place where the contour line overlaps is a steep cliff.

3. Explain the slope according to the density of contour lines.

On the same contour topographic map, dense contour lines represent steep slopes and sparse contour lines represent gentle slopes.

4. Quantitative calculation

(1) Compare the slopes of several points. If these points are not on the same map, calculate the slope according to the formula: slope = vertical relative height/horizontal distance.

(2) Calculation method of cliff height

(Note: △H is the height of the cliff, X is the number of contour lines falling on the cliff, and D is the vertical interval. )

Interpretation of isotherm diagram

On the meteorological and climatic thematic map, points with equal temperatures are connected by smooth curves, which is called isotherm map. On the isotherm diagram, the temperature of the same isotherm is equal, and isotherms with different values cannot intersect.

1. Judge the temperature value of a place.

From the low latitude to the poles, the temperature gradually decreases. The numerical value in the northern hemisphere increases from north to south, and the numerical value in the southern hemisphere increases from south to north.

2. Determine whether the northern and southern hemispheres are land and sea.

According to the change of isotherm temperature, the temperature decreases (increases) from north to north (south) hemisphere; It is the southern hemisphere (northern hemisphere) that decreases (increases) to the south.

Step 3: Density

Isotherms are dense, indicating that the temperature level is very different; The isotherm is sparse, indicating that the temperature difference is small.

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At high latitudes, the temperature is higher than that in the same latitudes; In low latitudes, the temperature is lower than that in the same latitudes ("high and low" principle). If the isotherm is straight, the underlying surface properties are relatively simple.

5. Judge the time (season or month) of a place.

In the northern hemisphere, in the winter of 65438+ 10, the isotherm on the mainland is convex to the south (low latitude), while that on the ocean is convex to the north (high latitude). July (summer) is just the opposite. In the summer of 65438+ 10 in the southern hemisphere, the continental isotherm is convex in the south (high latitude) and the ocean is convex in the north (low latitude). This is due to the difference in thermal properties between land and sea.

6. Determine the direction of ocean currents and cold and warm air currents.

When the isotherm distributed in the ocean suddenly bends in the same direction regularly, there must be an ocean current passing by, and the direction in which the isotherm protrudes is the flow direction of the ocean current. A warm current protrudes from a lower latitude to a higher latitude (or flows from a higher altitude to a lower temperature sea area); On the contrary, it is a cold current.

7. Calculate the altitude of a place according to the distribution of isotherm.

In the troposphere, the temperature decreases with the increase of altitude, and its coefficient of variation is 6℃/1000 m.

8. Analyze the main factors affecting the temperature distribution in a certain place.

① If the isotherm is roughly parallel to latitude, it means that the area is mainly affected by latitude factors. Affected by the intensity of solar radiation, the temperature drops from low latitude to high latitude.

(2) If the isotherm is parallel to the coastline, it shows that this area is significantly affected by the difference of thermal properties between land and sea. The farther inland in summer, the higher the temperature; Winter is the opposite.

(3) If the isotherm is parallel to the contour line or the trend of mountains, it means that the temperature in this area is affected by topography.

1. Judging the distribution law of isotherms

(1) Determine the hemisphere position according to the gradual change law of isotherm values.

From a global perspective, whether it is June+10 or July in 5438, the temperature distribution is decreasing from low latitude to high latitude. According to the gradual change law of temperature value in the north-south direction, which hemisphere the area belongs to can be judged. For example, the isotherm value of a region decreases from south to north, that is, in the northern hemisphere; If it decreases from north to south, that is, in the southern hemisphere, there may be a phenomenon of high temperature in the middle and decreasing in the north-south direction, then this area is near the equator.

(2) Judging the temperature difference according to the density of isotherm.

On the same graph, dense isotherms indicate large temperature difference, while sparse isotherms indicate small temperature difference. For example, it can be seen from the isotherm distribution maps of China in June and July that the isotherm of China in June is denser than that in July, so it can be judged that the temperature difference between north and south in China in June is larger than that in July.

Knowledge of geographical isoline in college entrance examination 3

Interpretation of Isobar Diagram

1. Judging the air pressure system

Isobar is closed, and the numerical value is low-high-low pressure center (cyclone); Isobar is closed, with high numerical value in the middle and low periphery-high pressure center (anticyclone); A long and narrow area where high pressure extends-high pressure ridge; A long and narrow area extending from low pressure-low pressure trough, etc.

2. Judge the size of the wind.

According to the density of isobars, where isobars are dense, the air pressure difference per unit distance is large and the air pressure gradient force is large, so the wind force is large; In sparse places, the pressure gradient force is small, so the wind force is small. Tanlaoshi geography studio comprehensive arrangement

3. Judge the wind direction at any point

According to the pressure level, the direction of the horizontal pressure gradient force (perpendicular to the isobar, from high pressure to low pressure) is determined first, and then the deviant wind is drawn according to the law of deviatoric force (right in the northern hemisphere and left in the southern hemisphere).

Judge the weather conditions

When the low pressure and low pressure trough are controlled, it will rain continuously; How sunny it is when high pressure and high pressure ridge control; The cold front rain area is behind the front, and the warm front rain area is before the front. The wind blowing from the low-latitude sea surface to the high-latitude land is mostly warm and wet. The wind blowing from the high latitude inland to the low latitude area is mostly cold and dry.

5. Interpretation of frontal cyclone

① Determine the front position (on the low-pressure groove), and the front line coincides with the groove line; ② Determine the wind direction near the front; (3) Determine the nature and moving direction of the front (cold front when the cold air mass actively moves to the warm air mass, and warm front when the warm air mass actively moves to the cold air mass).

1. Determine the names of various parts of the pneumatic system.

In the isobar diagram, the isobar is closed, and the central air pressure is higher than the surrounding air pressure, which can be judged as high air pressure; On the contrary, it is low pressure. The part where the isobar of the high pressure center bends greatly is called the high pressure ridge, and the connecting line of the maximum bending point of each isobar is called the ridge line; The part where the isobar in the center of low pressure bends greatly is called the low pressure trough, and the connecting line of the maximum bending point of each isobar is called the trough line.

Judging wind power

On the same picture, according to the density of isobar, the magnitude of wind can be judged. Generally speaking, the isobars are dense, indicating that the pressure difference in this area is large, the horizontal pressure gradient force is large, and the wind force is also large; The sparse isobar shows that the pressure difference in this area is small, the horizontal pressure gradient force is small, and the wind force is small.

3. Judge the wind direction and weather conditions

Mark the wind direction at a point near the ground. Firstly, determine the direction of the horizontal pressure gradient force at a certain point, that is, from high pressure to low pressure and perpendicular to the isobar; Then, according to the direction of pressure gradient force, the wind direction in the southern hemisphere is to the left and the wind direction in the northern hemisphere is to the right.

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