Isoline Maps

Isoline maps are another type of thematic map. Isoline maps use line symbols to portray a continuous distribution such as temperature or elevation. Isolines are lines that connect points of equal numeric value. A contour map showing elevation above sea level is a type of isoline map. The map above shows the surface dew point temperature in the United States at a particular point in time. The red areas are the regions where water vapor has saturated the air at the highest levels. The higher the dew point temperature, the more likely the area will experience fog. The lower the dew point, the drier the air and the higher chance for fire danger.