For a map with a graticule, what direction does the meridian represent?

On a map with a graticule, the longitude lines indicate the north-south direction.

Meridian is a virtual straight line that defines the east-west direction on the earth. They divided the earth into two hemispheres, north and south, and marked the north-south direction. In geography, the concept of meridian is very important, because it can help us determine the position and direction of any point on the earth.

Meridian means north-south direction, that is to say, at any point on the earth, meridian points in two directions. Specifically, the northern end of the meridian points to the North Pole and the southern end points to the South Pole. This means that if you stand at any point on the surface of the earth, facing the north, the south is behind you. Similarly, facing south, the back is north.

The north-south direction indicated by the meridian is of great significance for determining the geographical position as follows:

1. Determine geographic coordinates: longitude and latitude lines are the basic framework of geographic coordinate system. By measuring longitude and latitude, we can accurately determine the position of any point on the earth. Longitude indicates the position of a point in the east-west direction, while latitude indicates the position of a point in the north-south direction. Combined with latitude and longitude coordinates, we can accurately describe the position of any point on the earth.

2. Navigation and route planning: In the field of travel and transportation, latitude and longitude coordinates are very important for navigation and route planning. Modern global positioning system (GPS) can accurately determine the position of ground receivers by measuring latitude and longitude. Based on these data, GPS system can provide us with accurate navigation and route planning guidance.

3. Scientific research: Meridian also plays an important role in scientific research. For example, the earth's rotation and period of revolution are calculated by measuring the direction of the poles and the sunshine time. These measurements are very important for accurate time calendar calculation and astronomical research.

4. Geopolitics and international boundaries: Countries, regions and political boundaries are usually divided according to latitude and longitude coordinates. The isomorphism of latitude and longitude forms the boundary line between countries and regions, which plays an important role in international politics and geopolitics.

5. Climate and meteorological research: Climate and meteorological research also depends on latitude and longitude coordinates. By measuring the latitude and longitude of different regions, we can determine the path and influence range of climatic zones and meteorological events (such as hurricanes, droughts and floods). This information is of great significance to disaster early warning, climate change research and environmental protection.