A rough idea of the conditions that do this would be: if the synoptic conditions oppose the local thermally-induced sea-land pressure gradient. Likewise the wind can go calm at the seashore at times even when a large thermal imbalance exists. All that, plus the reduced friction over water, mean seashores\large lakeshores tend to be some of the rarer land locations to see calm winds, as this hourly August wind climatology of a coastal Florida site shows (they only see calm winds 4.5% of the time) and other factors, too for my Florida situation, by midmorning winds often start to increase because heating is causing vertical mixing which brings stronger winds speeds down towards the surface from aloft. there's typically some regional pressure gradient. This doesn't mean the wind will definitely go calm when the sea and land are at equal temperatures. Would expect that the conditions at such a time would reflect the synoptic conditions at the time (the larger-scale regional conditions caused by the usual interplay between transient high and low pressures, airmass movement, vertical instability and mixing, etc). So there are many places that have long stretches of the year when the seabreeze tends to stay quite strong (for example, the Pacific coast of California in the spring and summer) (it may be obvious for people in most areas, but I have remind myself that a seabreeze doesn't equate to thunderstorms in most places most of the time!) Ocean currents can mean some areas have much cooler (or even warmer) water than the land airmass during long periods of the year. which would be most common after sunset \ midmorning. in our active seabreeze season in Florida, that would mean temperatures generally in the low 80s ☏ (upper 20s ☌). If one of the winds is a humid flow from a warm ocean such as the Gulf of Mexico, the result can be powerful thunderstorms and tornadoes.Thermal equilibrium suggests equal temperatures. On a smaller scale, colliding wind patterns can produce convergence, in which air also has nowhere to go but up. At the center of high-pressure areas, dry air descends from above, producing fair weather. This causes moisture to condense into clouds, producing storms. Winds reaching the center of a low-pressure area have nowhere to go but up. As it moves, however, it spirals due to the coriolis effect, producing the shifting winds we experience from day to day, as highs and lows drift under the influence of the prevailing westerlies. Air moves from areas of high pressure to low pressure. Within the mid-latitudes, weather effects create high- and low-pressure zones, called highs and lows, respectively. This is why so many weather events in the United States come from the west.Īt latitudes higher than about 60°, cold surface winds try to blow toward the Equator, but, like the trade winds, they are bent by the coriolis effect, producing polar easterlies. These winds are called the trade winds.įarther from the Equator, the surface winds try to blow toward the Poles, but the coriolis effect bends them the opposite direction, creating westerlies. The coriolis effect, an offshoot of the Earth's rotation, makes moving air masses curve, so that the winds converging on the Equator come from the northeast in the Northern Hemisphere and the southeast in the Southern Hemisphere. Lower down, air is pulled in from the north and south. Air rises here and spreads north and south, high above the land. The tropics, for example, are always hot. Similar forces produce global wind patterns that affect climate. Land breezes come at night, when inland temperatures drop enough that the ocean is now warmer than the land, reversing the effect. A similar effect can occur near big lakes, where the wind is referred to as a lake breeze. By late afternoon, a strong breeze can be blowing dozens of miles inland. Cooler air rushes in from the ocean to take its place and presto, a wind is born. Sea breezes occur when inland areas heat up on sunny afternoons. Two simple examples of this are sea breezes and land breezes. The energy that drives wind originates with the sun, which heats the Earth unevenly, creating warm spots and cool spots.
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