Land and Sea Breeze

One of the most important weather processes of the Baltic Sea, which emerge locally under high pressure weather conditions with low winds and intensive insolation, is the land and sea breeze circulation. 

This specific coastal wind system develops in dependence on the temperature difference between water and land, and the gradient wind between the highs and lows at the ground (Loth, 1988). 

In the late morning, when the coast and the hinterland are strongly heating up, the air pressure in the near-surface layers is lowering in these regions as a result of ascending warm 

FIGURE 4.21 Sea breeze cloudiness at the Baltic Sea coast, Rostock, September 25, 2004 (photo Tiesel). Color figure on CD, Chapter 20.4. 

Typical for the onshore breeze, its sea wind front is formed above the almost waveless Baltic Sea, which is apparent by an increasing rippling of the seawater surface. Along with the front s rapid passage across the coastal region, not only wind direction and wind velocity do suddenly change but also a local abrupt transition from the continental to the maritime weather takes place. 

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Land and sea breezes are wind and weather phenomena associated with coastal areas. A land breeze is a breeze blowir from land out toward a body cf water. A sea breeze is a wind blowing from the water onto the land. Land breezes and sea breezes arise because of differential heatir between land and water surfaces. Land and sea breezes can extend inland rp to 100 mi (161 km), or manifest as local phenomena that quickly weaken with a few hundred yards cf the oreline. On average, the... 

Land and sea breeze patterns can greatly influence fog distribution and pollution accumulation or dispersion over inland areas. Current research on land and sea breeze circulation patterns also include attempts to model wind patterns that affect energy requirements (e.g., heating and cooling requirements) in affected areas as well as impacts on weather dependent operations (e.g., aircraft operations). 

On an average, the land and sea breeze system of the Baltic Sea is up to 200 m high, extends about 300 m toward the Baltic Sea and about 500 m into the hinterland. During the high pressure weather periods in May and June, when the Baltic Sea water is still relatively cold, the sea breeze system of the Baltic Sea is formed most intensively. If in such cases onshore gradient wind exists under certain weather conditions, it is significantly... 

Table II summarizes the estimates obtained In the NILU study when using the methodology outlined above. Results for the Haga site have been boxed In for later comparison with results obtained using the cluster validity discriminant. The lower values for the 24h samples probably reflects their being collected when there was little land- or sea-breeze for transport of the emissions from the smelter. Daytime sea breezes would tend to transport emissions toward and past the Haga site, while the evening landbreezes would tend to transport emissions back toward the Haga site.

Breezes are induced by temperature contrasts between land and sea they are characteristic of the entire Black Sea coast. The greatest recurrence of breezes universally fall in the period from March to October on the southern coast of the Black Sea, they are probable throughout the entire year. 

The greatest number of days with breezes (more than 50 days/year, at places up to 190 days/year) is noted on the southern coast of the Crimea, where the temperature contrast between land and sea is best expressed. Along the Caucasian coast, the recurrence of breezes increases from the north to the south from 18 to 50 days/year. Breezes are most rarely encountered on the western and northwestern coasts of the Black Sea and in the Kerch region. 

Because land breezes and sea breezes are localized weather patterns, they are frequently subsumed into or overrun by large-scale weather systems. Regardless, winds will always follow the most dominant pressure gradient. 

During the daytime the land and sea receive approximately equal amounts of heat from the Sun, but the much smaller heat capacity of the land causes its temperature to rise more rapidly. This causes the air above the land to heat, reducing its density and causing it to rise. Cooler oceanic air is drawn in to vill the void, thus giving rise to the daytime sea breeze. 

Fig. 17-17. Sea breeze due to surface heating over land, resulting in thermals, and subsidence over water.

Its equations account for advection, Coriolis effects, turbulent heat, momentum, moisture iran.sport, and viscosity. The system treats diurnaliy varying winds such as the land-sea breeze and... 

In coastal areas, temperature differences between the land and the water produce air pressure variations, creating sea and lake breezes that are superimposed on the normal winds. These winds vai"y diurnally and as a function of cloudiness. During the daytime, winds blow from the cool sea toward the warm land, while at night the land becomes cooler than the sea surface, and the winds blow from land to sea. 

At scales smaller than the synoptic scale, topography and differences in the surface cover (e.g., forest, agricultural fields, open water, or urbanized land) influence local winds, precipitation, and temperature. One common example of a local effect due to surface cover is the sea breeze, which occurs because water bodies warm and cool more slowly than the land does. During the day in coastal areas, air over the land warms and rises more rapidly and is replaced by cooler air originating from over the water. The reverse may happen at night, as the land cools to a temperature lower than that of the water body,... 

Figure 13. The sea breeze. On a sunny day the land heats up faster than the sea, as the sea has a larger heat capacity and is a better conductor of heat. The air over the land is heated and rises, generating an onshore sea breeze (after ARIC, 2006)...

Mesoscale. Phenomena occurring on scales of tens to hundreds of kilometers, such as land-sea breezes, mountain-valley winds, and migratory high- and low-pressure fronts. 

The figure also includes land breeze data from two different altitudes, 90 and 1800 meters, which were obtained within 2 hours of each other from a circling aircraft. Again we see deviations from sea water ratios with increasing altitude for Cl/Na. The absolute values of the ratios containing F also show this change, but are different from marine aerosol ratios. In this case, however, the wind was from the land and the samples were collected about 150 miles from the U. S. east coast. The influence of a continental aerosol component did appear in the fluoride concentration (12). Similarly, changes in the relative chemical composition of marine aerosols with altitude have been reported by others for SO4/CI (2, 51) and Cl, Br, and I (44). 

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