What Are Contour Lines in Cartography?
Contour lines in cartography are imaginary lines that join points of equal elevation above a given baseline level, such as mean sea level or benchmark. These lines are often used to represent hills and valleys on a map and can be used to measure the steepness and shape of a terrain.
Understanding the Basics of Contour Lines
Contour lines are used to show the change in elevation of a terrain. Each line represents a certain altitude, with the intervals between the lines determined by the scale of the map. The closer together the lines are, the steeper the terrain. Contour lines can also be used to measure the angle of a slope, as well as the distance between two points.
Characteristics of Contour Lines in Surveying
No Two Lines Intersecting:
Contour lines in surveying for reading contour maps do not intersect each other in any case. All the lines close themselves within the map boundaries or outside it.
Indication of Steep Slope:
If the contour lines are very close to each other, this indicates steep slope. On the other hand, if the contour lines are at very large distance to each other, this indicates a gentle slope.
Representation of Hill or Mountain:
If the closed lines have higher elevation in the center then it represents the hill or mountain. It is important to note that in a single contour line, at any point the elevation is same.
Depression in the Ground Profile:
If the closed line have increasing elevation as we move away, then it represents a pond or a depression in the ground profile. This helps surveyors to map the entire area correctly.
Types of Contour Lines in Surveying and their Importance
Contour lines are differentiated into many types based upon the function it denotes, they are listed as below:
- Isopleth
- Isohyet
- Isobar
- Isobath
- Isohaline
- Isotherm
- Isohel
- Isohume
- Isoneph
- Isopectic
- Isotach
- Isogeotherm
Following are the uses and importance of different types of contour lines in surveying:
1. Isopleth
What Is an Isopleth on a Contour Map?
An isopleth, or contour line, on a contour map is a line connecting points of equal value for a specific measurable quantity. This quantity can be related to geographical or meteorological phenomena, such as population density, elevation, air temperature, or wind speed. By plotting isopleths on a map, it is possible to visualize the spatial distribution of a particular quantity. For example, population density is calculated by dividing the population of an area by its surface area, and isopleths can be used to visualize the population density of a region.
2. Isohyet
What is Isohyet?
Isohyet is a line on a map that connects points of equal rainfall in a given area. It is used to measure and compare the amount of precipitation that falls in different parts of an area over a certain period of time. Isohyet lines are often used to help predict flooding and other weather-related events.
3. Isobar
What are Isobars?
Isobars are lines on contour maps that indicate points of equal or constant atmospheric pressure for a given period. This type of contour is used in the prediction of future weather patterns and is commonly used in television weather reporting.
What is the Purpose of Isobars?
Isobars are used to help meteorologists and other weather professionals predict future weather patterns. By plotting isobars on a contour map, meteorologists can better understand how pressure systems are interacting and how they will affect the weather. This information is then used to create forecasts and weather warnings.
4. Isobath
What are Isotherms?
Isotherms are contour lines on a map or chart that connect points with the same temperature. They are typically used to represent the temperature of a body of water such as an ocean, sea, or lake.
Understanding Isotherms
Isotherms provide a visual representation of the temperature of a body of water. They are an important tool for measuring and predicting changes in the temperature of a body of water, which can have a significant impact on various living organisms.
The Benefits of Isotherms
Isotherms are an important tool for scientists, researchers, and other professionals who need to understand and predict changes in the temperature of a body of water. By tracking isotherms, professionals can better prepare for changes in the environment and plan accordingly.
5. Isohaline
What are Isolines?
Isolines are a type of contour lines on a map which connect points of equal value. In the case of water bodies, this is typically the salinity of the water. Isolines can help indicate the shape, size, and distribution of salinity levels in a given area.
How Are Isolines Used?
Isolines are used to represent the salinity of a water body on a map. This helps give a visual representation of the water’s salinity levels, which can then be used to inform decisions about fishing, navigation, and other activities. Isolines can also be used to study the effects of climate change and pollution on a water body.
6. Isotherm
What is an Isotherm?
An isotherm is a type of contour line on a map or chart that connects points of equal temperature in a given area. It is typically used in meteorology to illustrate temperature patterns across a region.
Types of Isotherms
Isotherms can be divided into two main types: isocheims and isotheres. Isocheims are lines of equal mean winter temperature, while isotheres are lines of equal mean summer temperature. An isotherm at 0 degree is referred to as the freezing level.
Conclusion
Isotherms are useful for visualizing temperature patterns in a given area. By analyzing the placement of isotherms on a map or chart, meteorologists can better understand the climate of the region.
7. Isohel
What is an Isopleth of Duration?
An Isopleth of Duration is a type of contour line on a map that connects points of equal duration of sunshine for a given period.
How Are Isopleths of Duration Used?
Isopleths of Duration are used to visualize and compare the amount of sunshine different locations receive over a certain period. They can be used to help plan activities that require a certain amount of sunlight or to compare the climate of different locations.
What Are the Benefits of Using Isopleths of Duration?
The use of Isopleths of Duration allow for easy visualization of the amount of sunlight received by different locations. This can be helpful for planning activities that require a certain amount of sunlight, such as outdoor sports or gardening. Additionally, they can be used to compare the climate of different locations.
8. Isohume
What are Isohyets?
Isohyets are a type of contour line used to represent relative humidity on a map. These lines are drawn on a map to show areas of equal relative humidity levels. Isohyets can be used to analyze the climatic conditions of an area and identify areas of high or low relative humidity.
9. Isoneph
What Is a Cloud Line?
A cloud line is a line that connects all points of equal amount of cloud cover. It is used in meteorology to measure and analyze the coverage of clouds within an area. This line can help meteorologists understand the formation and movement of clouds, as well as the amount of precipitation in a given area.
10. Isopectic
What are Isopectic Lines?
Isopectic lines are imaginary lines on a contour map or chart that connect all the points at which ice forms simultaneously. These lines are used to represent the spatial distribution of ice formation and can help to identify areas of potential danger due to icy conditions. They are also used to monitor and track changes in ice formation over time.
11. Isotach
Wind Speed Isogon
A wind speed isogon is a line that connects all points of equal wind speed. This line can be used to map out the overall wind speed of an area, giving people an idea of what type of wind conditions they might experience in any given location. Wind speed isogons are often used in meteorology, aviation, and other industries that rely on accurate wind speed measurements.
12. Isogeotherm
What is an Isogeotherm?
An Isogeotherm is a line on a contour map that connects all points within the earth that have the same mean temperature. Contour mapping is a method of representing spatial variation in data, such as topography or temperature, across a region. The lines on a contour map represent points of equal temperature. An Isogeotherm is a line that connects all points with the same average temperature.
