Average sea level pressure in Northern Hemisphere summer and winter

Figure 1-3  Northern hemisphere summer (June–August) versus winter (December–February) plots of the annual average atmospheric pressure at sea level (SLP). In June–August (left), the area of strong average high pressure (orange) that extends across the CNP corresponds to the NPH. In December–February (right), the area of strong average low pressure (purple) centered on the Gulf of Alaska corresponds to the Aleutian Low. (Courtesy of NOAA ESRL Physical Sciences Division.)