![]() The coastline to have winds for good sailing. Light to calm (bad sailing), you can still get enough sea-breeze near In synoptic high-pressure regions where the synoptic-scale winds are.Caution, the sea-breeze can die in the late evening BEFORE the sun sets, so plan ahead to return to port before the winds die. Mid-day through mid-afternoon local time. Under these conditions, the sea breeze is strongest Sea breeze is strongest during clear sunny daytimes under High.Tend to be higher around sunset when the mean wind and the diurnalĬomponent are in the same direction, than around sunrise when they If the synoptic-scale wind (i.e., windĭriven by larger-scale pressure patterns like Lows and Highs) in theĪbove example is blowing from the north, the surface wind speed will The sea-breeze wind and the mean (24 h average) synoptic-scale The evening, easterly near midnight, and southerly (alongshore) near Westerly (onshore) during the mid-day, northerly (alongshore) during Hemisphere, the diurnal component of the surface wind tends to be For example,Īlong a meridional coastline with the ocean to the west in the Northern Hodograph has an elliptical shape (see Figure below). Rotation is clockwise in the northern hemisphere andĬounterclockwise in the southern hemisphere. The CoriolisĮffect causes the horizontal wind direction to rotate throughout theĬourse of the day. Reversing directions during the morning and evening hours. Onshore (coming from the sea during the sea breeze) and offshore (coming from the land as a land breeze), In the vertical cross section normal to the coastline (as in theįigure above), the surface wind oscillates back and forth between The return flow aloft is from the ocean toward land. In the land breeze, low altitude winds flow from land toward ocean, and Over land causing the land surface to get relatively cold, but in the ocean the cooling is spread over tens of meters at night. The reason is thatĪll of the heat loss at night is concentrated in the top few cm of soil Relative to the sea (assuming clear skies). The coast are 4 to 40 km/h (=1 to 10 m/s) with typical values of aboutĪt the end of the day, the sea-breeze circulation dissipates and a weaker, reverse circulation called the land-breezeįorms in response to the nighttime infrared cooling of the land surface When fully developed, near-surface wind speeds in the marine, inflow portion of the sea breeze at In early morning, the sea-breeze circulation does not extend veryįar from the coast, but spreads out further over land and over water as theĭay progresses. Increasing distance from the shore as the marine air is heated by the The TIBL is a region of warmed air that grows in depth with Even without mountainīarriers, the sea breeze will eventually turn away from its advance dueĪs the cool marine air flows over the land, a thermal internalīoundary layer (TIBL) forms just above the ground (see figure above). Mountains or by opposing synoptic-scale winds. The day, although typical advances are 20 to 60 km unless inhibited by The sea-breeze front can advance 10 to 200 km inland by Interface between the cool onshore sea breeze and the warm return flowĪloft. Kelvin-Helmholtz waves (KHW) can form at the Which can grow into a line of thunderstorms if the atmosphere is Is humid enough, a line of cumulus clouds can form along the front, Marine air over land and behaves similarly to a weak advancing coldįront or a thunderstorm gust front. Marks the leading edge of the advancing cool The solar heat is concentrated in the top few centimeters. Turbulence over several meters or more of ocean depth, but on land all Warms more slowly than the land during a sunny day is that sunlight isĪbsorbed and spread (diluted with cooler deeper water) by ocean There is also a weak return flow aloftįrom land to sea (see sketch below). The sea breeze is caused by a 5 ☌ or greater temperature differenceīetween the sun-heated warm land and the cooler water. Of crops adjacent to drier land with less vegetation). With different land-use characteristics (e.g., moist irrigated fields Inland sea breezes form along boundaries between adjacent land regions Similar flows called lake breezes form along lake shorelines, and It occurs in large-scale high-pressure regions of weak or calm synoptic-scale wind under mostly clear skies. Sea breezes, land breezes, katabatic winds, and coastal (barrier) jets.Ī sea breeze is a shallow cool wind that blows onshore (from sea to land) during daytime (see figure below). Local Winds Learning Goal 10a: Explain how the following local winds work and how they apply to sailing:
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