The difference in average water temperatures between one side of the Cape and the other may have its effects on the local weather. During the fall especially, when cold air moves over the waters of Nantucket Sound they may be covered with fog, whereas it can be bright and clear over the Bay, only a few miles distant. The normal kind of fog occurs when warm, moisture-laden air moves over cool or cold water, and is quite common in spring and summer. When a cold, dry air mass, on the other hand, moves over warmer waters it may result in what is called “Arctic sea smoke” a kind of wispy, steamy fog in turbulent, rolling air, rising to ten or fifteen feet above the surface of the water. During the winter Cape Cod is also subject to rapid changes in temperature depending on whether the wind comes from the northwest, with cold, dry, continental air, or from east and south off the ocean, the latter being seldom below the freezing point. The tip at Provincetown has much the same temperature as the sea island of Nantucket. On the other hand the town of Barnstable on the lower Cape may have an average summer temperature which is slightly warmer than Provincetown and a colder temperature in winter, since it is that many miles closer to the interior. I have driven down the coast from Boston several times during snowstorms when an area as close to the Cape as Plymouth was completely covered with snow; and as I drove south the storms turned to heavy flakes of wet snow on the near side of the Cape Cod canal and then to rain as I went on. The sea’s capacity to store up solar energy means that it exercises a moderating influence on the Cape, which is warmer during the winter than the mainland and cooler during the summer. Also, there are less thunderstorms on Cape Cod during the summer months than on the mainland, and the annual rainfall is likely to be lower because there is less showery precipitation, although local residents might be justified in thinking that water was on them much of the year in one form or another, as fog, salt spray, rain, or humidity. The late fall and winter is often characterized by cold, raw windy days, with the temperature just above freezing or at the freezing point, and the air is loaded with moisture from the sea and sometimes smells of it. During heavy storms the wind drives the salt spray inland with great force, depositing coats of salt on houses, telegraph poles, and wires.