中学地理的等值线有很多种类型,如等高线、等温线、等压线、等降水量线、等盐度线、等酸雨pH值线、等太阳辐射量线、等太阳高度线、等震线、等时线等。其中,等高线、等温线和等压线最重要。地理事象的空间分布、空间演变以及地理各要素之间的相互联系都可以通过等值线图来展示。它可以充分考查学生的空间概念、空间想像,以及分析计算能力,历年来高考都非常重视对等值线图的考查。所以,了解等值线的基本特点,把握等值线图的判读方法非常必要。一、等值线图的基本特点1.同一条等值线上的各点数值相等。2.等值线为闭合曲线,但有时受图幅限制,不能完整显示。3.两条等值线一般不能相交,陡崖除外。4.同一图中相邻两条等值线间的数值差相等。如等高线图上的等高距相等。5.在同一组等值线图中,等值线的疏密反映数值变化的大小(疏一小、密一大)。如,等高线的疏密反映坡度的陡缓(疏一缓、密一陡);等压线的疏密反映风力的大小(疏一小、密一大)。6.在同一组等值线图中,等值线的弯曲程度反映数值的变化程度,弯曲大则变化大、弯曲小则变化小。例如,南半球的等温线比北半球平直,是因为南半球海洋广阔,气温变化小。二、等值线图的判读方法及应用 High school geography contour there are many types, such as contour lines, isotherms, isobars, such as precipitation lines, such as salinity lines, and other acid rain pH lines, and other solar radiation lines, such as the sun line, Isochondral, isochronal and so on. Among them, contour lines, isotherms and isobars are the most important. The spatial distribution of geographic events, their spatial evolution, and the interlinkages between the various elements of the geography can all be illustrated by contour maps. It can fully examine the concept of space students, space imagination, as well as analysis and calculation capabilities, over the years the college entrance examination attaches great importance to the contour map examination. Therefore, it is necessary to understand the basic characteristics of isoline and to grasp the interpretation method of isogram. First, the basic characteristics of the contour map 1. The same value of each point on the same value. 2. contour is closed curve, but sometimes limited by the map, can not be fully displayed. 3. The two contour lines generally can not intersect, except for steep cliffs. 4. In the same figure, the two adjacent isoline are equal in value. Such as contours on contour contour equal. In the same set of contour maps, the density of the contour lines reflects the magnitude of the numerical changes (sparse, dense and large). For example, the density of the contour lines reflects the steep slope (sparse, dense and steep); the density of isobaric lines reflects the size of the wind (sparse, dense and large). 6. In the same set of contour maps, the degree of curvature of the contour reflects the degree of change of values, large changes in bending, and small changes in bending. For example, the isotherm in the southern hemisphere is flatter than in the northern hemisphere because of the vast expanse of the ocean in the southern hemisphere and small temperature changes. Second, the interpretation of contour map method and application