Surface weather analysis isotherms (lines of equal temperature), and isotachs (lines of equal wind speed) are drawn. The abstract weather symbols were devised to take up the least room possible on weather maps. A synoptic scale feature is one whose dimensions are large in scale, more than several hundred kilometers in length. Migratory pressure systems and frontal zones exist on this scale. Centers of surface high- and low-pressure areas that are found within closed isobars on a surface weather analysis are the absolute maxima and minima in the pressure field, and can tell a user in a glance what the general weather is
Intrapleural pressure Intrapleural pressure In physiology, intrapleural pressure (also called intrathoracic pressure) refers to the pressure within the pleural cavity. Normally, the pressure within the pleural cavity is slightly less than the atmospheric pressure, in what is known as "negative pressure". When the pleural cavity is damaged/ruptured and the intrapleural pressure becomes equal to or exceeds the atmospheric pressure, pneumothorax may ensue. Intrapleural pressure depends on the ventilation phase, atmospheric pressure, and the volume of the intrapleural cavity. At rest we have a negative intrapleural pressure. This gives us a transpulmonary pressure expanding the lungs. Intrapleural pressure is sub-atmospheric. This is due