Criteria for sea breezes:
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Inland temperatures greater than temperature of coastal waters;
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A moderate depth of dry convection to, say, between 750 and 900 m (2500 to 3000 ft)
is required before the sea breeze can become established;
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If the air is so stable that the convection is confined to a very shallow layer there will
be little or no penetration of the sea-breeze regardless of the temperature
difference between land and sea;
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Only a weak offshore wind component of <14 knots at 3000 ft initially;
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Convection to 1500 m (4000 ft) favours deep inland penetration (deep convection, leading
to shower or thundery activity, tends to halt the sea-breeze);
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Significant inland penetration is only likely if offshore 3000 ft wind is <10 knots.
Calculation method:
The calculator applies the density current equation from Simpson’s Sea Breeze and Local Winds and
subsequent research by David Jameson (Operational Meteorologist, Wattisham Met. Office).
$$v_{sbf} = 0.87 \left(\sqrt{gD \frac{\bigtriangleup \rho}{\rho}} \right) - 0.59U_g - \tau$$
The constants 0.87 and 0.59 were derived through experimentation along the south coast of England.
D = depth of sea breeze circulation (usually 350 m). The fraction is the density excess of the post sea
breeze front air,
g = 9.81 and
τ is a resultant action working against the sea breeze front inland
propagation, a direct result of turbulent mixing at the frontal boundary. This is at a maximum at max
diurnal heating, but wanes during the evening.