Contour line factors in a weather system. An isobar (from or "baros", meaning 'weight') is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure. More accurately, isobars are lines drawn on a map joining places of equal average atmospheric pressure reduced to sea level for a specified period of time. In meteorology, the barometric pressures shown are reduced to sea level, not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict
Atmospheric railway by atmospheric pressure. The train consisted of ten carriages (including that to which the piston is attached) and its weight was upward of fifty tons. At seven and a half minutes past two the train left the point of rest at the Dartmouth Arms, and at eight and three-quarter minutes past, the piston entered the valve, when it immediately occurred to us that one striking advantage of the system was the gentle, the almost imperceptible, motion on starting. On quitting the station on locomotive lines we have frequently experienced a "jerk" amounting at times to an absolute "shock" and sufficient