The sea temperature in a region of the United States remains very low, at just 12 degrees Celsius, while the air temperature is scorching hot, nearing 40 degrees Celsius. What causes this phenomenon?
When visitors arrive at the Jersey Shore (New Jersey, USA) and plan to swim in the ocean (which here refers to the Atlantic Ocean), lifeguards immediately remind them to be cautious. The reason is that the sea water here is very cold, only 12oC.
Meanwhile, just two buildings away from the beach, the weather is scorching, with everyone sweating and air temperatures ranging from 35 to 38oC (from hot to extremely hot).
Joe Bongiovanni, the beach safety supervisor, stated that the sea temperature here consistently remains cold during heat waves, only rising to about 20 to 21oC at the end of July and August—times when the air temperature on the shore is very high. Therefore, many people, feeling hot, rush to the beach only to shiver from the cold water.
A lifeguard running into the cold water at Jersey Shore for training. (Photo: Andrew Mills/ NJ Advance Media for NJ.com).
Authorities in the area explain that the phenomenon of cold sea water is due to a process called “upwelling,” which can occur in various ocean regions worldwide, not just in New Jersey.
Specifically, strong winds from the South and Southwest push warmer surface water down or away, causing cold water from the depths to be stirred up and “rise” to the surface. As a result, the sea temperature in that area becomes very low. Additionally, this “upwelling” process makes the waters at many beaches along the Jersey Shore very clear and clean.
An illustration of the “upwelling” phenomenon: The orange arrows indicate warm surface water being pushed away, while the dark blue arrows show cold water from below rising to the surface. (Photo: NOAA).
Residents in the area mention that even on the hottest days, standing close to the shore, the cold breeze from the sea can make them feel the need to wear a sweater, while just a block away, people are comfortably wearing regular t-shirts and still feel hot.
