What Are Isolines?

Joins points where the amount of cloud cover is the same. The idea of lines that join points of equal value was rediscovered several times.

Contour line

If there is little or no content on the base map, the contour lines may be drawn with relatively heavy thickness. Joins points of the same value as a number , such as population or car ownership.

A third form of distribution after spatially extensive and punctiformal is linear. Second, two different isolines cannot cross each other. Isobars are commonly used in television weather reporting. It was assumed that each catering outlet was selling the same volume of trout.

In interpolating the isopleths in Figure 5. At the medium scale all main and secondary road routes would be shown, and at the 1: A reservoir might have been built on a waterway since collection of the flow rate data commenced.

On a transparent overlay three concentric rings were drawn, each consecutively corresponding to 12km, 24km and 36km radii at a 1: These are maps which depict average values per unit of area over some administrative region for which statistics are available, such as density of population or a yield per unit area of land Figure 5. This can give an adequate indication of adverse slopes, i. Sometimes intermediate contours are present in flatter areas; these can be dashed or dotted lines at half the noted contour interval.

Examples of small-, medium-and large-scale topographic maps are shown in Figure 5. Single and Multivariable 6 ed.

Geographical information systems and remote sensing in inland fisheries and aquaculture

Date visited. Pilbeam, Ordnance Survey: An isochalaz is a line of constant frequency of hail storms, and an isobront is a line drawn through geographical points at which a given phase of thunderstorm activity occurred simultaneously.

A line representing points of equal annual change in magnetic declination. Using the formulae:. Dot maps.

By contour planting and contour ploughing , the rate of water runoff and thus soil erosion can be substantially reduced; this is especially important in riparian zones.

Joins points where it costs the same to transport products from where they are made to where they are sold. Figure 5. Placing the central point of the concentric rings over the mid-point of each cell in turn, the number of catering outlets within each of the three market zones was counted.

Larger scale topographic maps give an indication of the extent of built-up areas, and the distribution of and density of the settlement pattern shown will give an indication of retail market size. Isopleths are thus lines which join all places having an equal value.