How do meteorologists know where to place the "L" and "H" on weather maps?

Generally speaking, in domestic meteorology, weather maps are marked with "L" and "N", or 'G' and 'D', which mean cold, warm, and high or low respectively. There is no H symbol in domestic weather maps. If so, it may be 'low' and 'high', which also means high or low. High and low refers to the high pressure center or low pressure center, which is generally calibrated based on the wind field and pressure field or height field observed on the ground or at high altitude. Low pressure in the Northern Hemisphere is generally at the center of the counterclockwise wind field, and high pressure is at the center of the clockwise wind field.

If there is an observation station and the wind direction is at the observation station, then the high and low pressure centers cannot be displayed on the observation station