In Meteorology, What Is an Isobar?

Isobaric line ^[1] , a meteorological term, refers to a closed line formed by connecting places with equal pressures within a certain time on a plan. Fill in the observed sea level pressure value on a map of sea level height. This kind of contour map with the same height can show the spatial distribution of the air pressure.

Each at the same time

Using the contour map, you can analyze the pressure distribution on the same horizontal plane, you can determine the location of high and low pressure, and compare and find the difference, and lay the foundation for the study of atmospheric motion ^[2]

Isobaric is a kind of contour, and must follow the common principles of contour analysis.

Equal everywhere:

On the same contour line, the element values are equal everywhere, that is, during analysis, the contour lines must pass through the stations with equal values.

One side is higher than the other:

The value on one side of the contour must be higher than the value on the other, that is, the contour should pass between a station above the contour value and a station below the contour value, not between Pass between stations that are above (or below) the contour value.

Closed curve, 3 no:

Contours cannot intersect, cannot branch, and cannot be interrupted.

Constant difference:

Between two high-value areas or two low-value areas, there must be two adjacent contour lines with equal values, and the values of these two contour lines are the lowest values between the two high-value areas. The highest value is between the two low value regions. There is a constant difference in values between the adjacent contour lines of the high-value area and the low-value area.

The isobars are dense and the horizontal pressure gradient force is large. vice versa.

An isobaric surface is a surface formed by points with the same air pressure in space. The isobaric line is a line formed by points with equal pressure on a horizontal plane. If the heating near the ground is uniform, the isobaric surface is a flat surface. At this time, the isobar surface can be considered to be parallel or coincident with the contour surface in the vertical direction. But as the altitude increases, the pressure decreases. Therefore, the isobaric surface is used to indicate the change of air pressure in the vertical direction.

The isobar is a case of high or low air pressure on a plane. Isobaric lines are used to indicate differences in air pressure over a horizontal plane.