![]() The large temperature discrepancy that occurred today can also largely be explained by the sea breeze. During some of our heat waves last summer with westerly or even west-northwest winds, the coastal areas often recorded the warmest temperatures, as Westhampton Beach, NY exceeded NYC’s temperature on a few occasions. Westerly winds also tend to downslope off the Appalachian Mountains, meaning the air descends, which allows it to compress and warm. This is one reason why the most widespread warmth throughout the entire area actually occurs on westerly winds: in the right weather pattern, westerly winds can still bring in the warm air that southerly winds can, but the westerly winds can “push” the sea breeze away. However, when the general weather pattern is favoring westerly winds or northerly winds, either behind a cold front, or when a large dome of high pressure is situated to our south and west, those winds can actually “collide” with the sea breeze and stop it from from occurring. Meanwhile, it was in the upper 70s in most of New Jersey, with winds generally less than half that of JFK. And as we can see, the sea breeze was not just relegated to the immediate coast - most of Long Island also had stronger winds and temperatures stuck in the low to mid 60s - the sea breeze was strong enough to penetrate well inland. At 5:00pm that day, JFK had a temperature of 61 degrees, with southerly winds at 35mph, gusting to 47mph! That’s equivalent to a weak Tropical Storm. This helped to combine with the sea breeze to increase the winds along the south-facing shores, and make temperatures much colder. In the example above, from April 14, we had a low pressure system to the north which was already bringing southerly winds to begin with. This is where the general weather pattern kicks in. Or at the very least, they do not always penetrate further than the immediate beaches. Of course, sea breezes do not occur every time it warms up during a spring or summer day. Also notice how in some areas, the southerly winds are stronger on Long Island compared to areas further west (Weather Underground). Notice temperatures approaching 80 in New Jersey with relatively light winds, yet much cooler and windier conditions on Long Island. Temperature and wind observations taken from Monday (4/14/14) afternoon at 4:48pm. This sinking air towards the sea surface reinforces the high pressure, which reinforces the source of air that is blowing towards the land, which reinforces the sea breeze. Now that this air is above the sea - where air at the surface is already heading towards the land - the air has to sink to replace the air that is leaving the sea. ![]() The air with higher pressure aloft on the land thus flows towards the area with lower pressure above the sea. However, over the sea, there is no air rising into the upper levels, so the pressure is relatively lower there. The circulation gets reinforced because when the air over the land rises, it creates an area of higher pressure at the upper levels of the atmosphere, since lots of air is rushing towards the upper levels. This air happens to be coming from the colder ocean, which helps to create colder temperatures and windier conditions along the coast. The atmosphere always wants to balance itself out, so to compensate for the air over the land escaping the surface, air from higher pressure has to flow towards it. The lack of rising air over the sea thus creates a slightly higher surface pressure, relative to the land. The rising air over the land creates a slightly lower surface pressure, since the air is escaping the surface, rather than exerting a force on it. However, the relatively cold ocean does not have this same heat, as it is more dense, so the air does not rise. Once the land heats up, thermodynamics dictate that the warm air must rise, since it is less dense. The sea breeze circulation (top) and land breeze circulation (bottom). ![]() Thus, during the day, the land will often be much warmer than the ocean. The ocean has a high specific heat capacity, which means that it can absorb the same amount of heat as the land does, but will not warm up nearly as much as the land. ![]() However, the sea is still relatively cold this time of year, especially considering how cold of a winter we had. Whenever we have a warm, springtime airmass, the temperatures over the land warm up quickly. The explanation for this is the sea breeze. Today was another one of those classic days where inland areas soared into the upper 70s, and coastal areas had trouble exceeding 60 degrees, with plenty of wind.
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