Sea Breeze
 
A sea breeze is a good example of an atmospheric circulation that arises at the boundary between the land and ocean. On a hot summer's day, many people flock to the beach to get away from the inland heat and experience a refreshing sea breeze. Sea breezes help to moderate the climate of coasts, and temperatures can often be 10˚C cooler along the coast than inland as a result. The sea breeze involves air blowing from the relatively cool sea towards the warm land surface, preventing temperatures rising significantly near the coast. At night, the opposing land breeze blows from the cool land surface out towards the warmer sea. 
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Polar Lows
 
A polar low can be described as an intense mesoscale area of low pressure that forms over the ocean polewards of the main polar front in both hemispheres. They typically last for a few days and have a diameter of 100 - 500 km. Polar lows have been descibed as "arctic hurricanes" because they share some features with their tropical cousins: they form over a warm sea surface (compared to a much colder atmosphere), and so can form as warm-cored systems which derive their energy from latent heat of condensation from the warm ocean. 

Due to their small size and short time-scales, polar lows were difficult to observe until the advent of satellite imagery in the 1960s, which revealed many small-scale cloud vortices at high latitudes in the winter. They can pose a threat to shipping and oil platforms in the polar oceans, due to the potential for storm force winds, high waves and heavy snowfall that they produce. Without a dense network of observations over the ocean and detailed satellite imagery, they can be difficult to accurately forecast.  
 
Schematic illustrating the sea breeze circulation. During the day, cool air flows from the ocean towards the land. Here it ascends and promotes cloud formation. Aloft, air flows back over the ocean, where it sinks and completes the circulation. 
Credit: MetEd/COMET. 
Water has a much greater specific heat capacity than land (the energy required to heat up 1kg of material by 1˚C), meaning that it takes much longer for the ocean to heat up and cool down than the land surface. Thus, the diurnal and annual temperature variation over the ocean tends to be much smaller than over land. During a warm day, the land heats up much quicker than the ocean, resulting in higher pressure over the ocean surface and lower pressure over the land. 
Since pressure surfaces expand in a warm air column and contract in a cold air column, this means that aloft, there is high pressure above the land and lower pressure above the ocean. This promotes the formation of a return circulation from the land to the ocean aloft, completing the circulation as this air cools and sinks to the surface over the ocean. The rising air over land allows the formation of covective clouds, while widespread sinking air over the ocean leads to mostly clear skies. 
Schematic of the pressure contours between the land and ocean during a sea breeze. Pressure is low over the land at the surface and high aloft. Conversely, pressure is high over the ocean at the surface and low aloft. 
Credit: MetEd/COMET.
Sea breeze fronts form on the leading edge of an advancing sea breeze as the cool oceanic air moves inland throughout the day. These are esentially mesoscale cold fronts and warm, land-based air is forced to ascend over them. As a result, sea breeze fronts are usually areas of enhanced cloudiness and can sometimes trigger showers and thunderstorms. The front is often marked by a well-defined line of cumulus clouds on a sunny day, with clear skies behind the front and out to sea.
Generally, conditions need to be calm and sunny for sea breeze formation. When there is a background synoptic wind, the location and advancement of the sea breeze is usually overwhelmed, either pushing it well out to sea if the synoptic wind is blowing from the land, or advancing it well inland if the synoptic wind is blowing from the ocean. Windy conditions tend to negate any temperature difference between the land and the ocean, however. On warm, calm days, the sea breeze may advance over 100 km inland! 

Schematic displaying a sea breeze front and the formation of cumulus clouds on its leading edge. Mixing between the two airmasses can lead to the formation of low-level cloud that marks the front. 
From: http://cliffmass.blogspot.co.uk/2013/08/sea-breeze-effects-on-clouds.html
Sometimes, the geography of the landmass can allow two sea breezes from opposing directions to converge. This convergence zone results in a region of enhanced lift that is much more likely to allow cumulus congestus and thunderstorms to develop. The Florida peninsula and Cuba are both good examples of sea breeze convergence zones, where the sea breeze produces a diurnal cycle of convective clouds and precipitation in the summer. The south-western coast of England can also favour sea breeze convergence under calm conditions in the summer. 
Visible satellite image showing sea breeze convergence over the Florida peninsula in spring 2014. The convergence zone leads to formation of a line of towering cumulus. 
Credit: GOES/NASA. 
Land Breeze 
At night, the land eventually becomes cooler than the sea, meaning that the horizontal pressure gradient shown above reverses. Low pressure is now situated over the ocean and high pressure over land, at the surface. A cool wind blows from the land towards the ocean, where convective clouds may form. Skies over the land are clear, under a large area of descending air. Land breezes tend to be weaker than sea breezes, because the temperature difference between the land and sea is generally less at night.