A Day at the Beach: Explained

Courtesy of Katie Thomas

During the summer everyone enjoys a day or a vacation at the beach, but do you really know about all the different weather and natural phenomena taking place in front of your sunglass covered eyes? Looking out at that large ocean in front of you while sitting on the beach, you may not realize all the wonders that are present where the ocean and shore meet. Phenomena like land and sea breezes, tides, wave activity and rip currents can produce a very interesting day at the beach.

Land and sea breezes are the patterns that describe wind movement between the sea and land. Wind breezes form because variances in temperatures cause a difference in barometric pressure, which leads to air/wind moving from a 

Source: NCSU

high-pressure area to a lower pressure area. This is the driving force behind land and sea breezes. During the summer months, there is a larger difference between the temperature of the land and the ocean because land absorbs heat from the sun quicker than water. During the day the land heats up, making the warmer air rise causing a low-pressure system to form at the surface. Meanwhile, over the cool ocean, high-pressure at the surface is formed due to cool air sinking. Then the air from the high-pressure (ocean) blows to the low-pressure (land) and you’ve got yourself a sea breeze. At night the roles are reversed as the land becomes cooler and the ocean remains warmer. Land and sea breezes are influential in daily beach weather. Fronts that are formed from sea breezes are known to trigger the occasional thunderstorm. This effect is regularly felt in the state of Florida because it is surrounded by the Atlantic Ocean and the Gulf of Mexico. So, one can state with a degree of confidence that we have active precipitation events at the waters edge due to the constant temperature change and mixing of high and low pressure systems; be it in a regional or localized setting. This is why one part of the coast can experience a strong rainstorm, but further up or down the same coast it is still calm.  Storms can roll in and out with great frequency along costal regions.

             Another driving force of dynamic weather at the beach is the ocean itself. The ocean is a large “sink” that absorbs a lot of the sun’s radiation from the earth’s atmosphere. Currents within the ocean help distribute warmer and colder water to respective areas. This helps regulate temperatures in different regions of the Earth. For example, the region around the equator absorbs more of the sun’s energy than it releases and the polar regions release more energy than they receive. To create a global energy balance, ocean currents regulate overall temperature and climates; this also makes the weather along the coast more dynamic than weather inland.  Without these ocean currents, regional temperatures would become too extreme and some areas would be uninhabitable.

Rising and ebbing tides and rip currents are another phenomenon found at the beach. As you may already know, there are high tides and low tides, which occur on a daily basis. Tides are so predicable that they are printed in newspapers and weather apps with a high degree of accuracy.  You may also know that the gravitational pull from the moon causes tides, but do you know how? The moon’s gravitational force creates “bulges” in the ocean on opposite sides of the planet.  These bulges are created by the moon’s gravitational force pulling water towards the moon and then away from it; these bulges subsequently cause high and low tides. When the moon is directly above you, you should be experiencing high tide. Then when the moon is directly overhead on the exact opposite side of Earth, you experience a low tide. Therefore, high and low tides are generally about 12 hours and 30 minutes apart. Another spectacle at the beach is rip currents. Most times rip currents can be more dangerous than anything else at the beach. Rip currents are created when waves travel to shallower water and some waves crash harder than others at points on the beach. This area becomes worn down as sand is pulled out to sea and begins to give way creating a break in the sand. This break allows for water to flow out to sea in a narrow channel at a much quicker pace than the surrounding water returning to the ocean. The concentrated stream of water has the power to possibly pull you out 200 yards or more. A sand bar, is a beach surface that is a few feet above the rest of the surf line, is what normally erodes and breaks and causes fast moving water to return to the ocean. So if you see a sand bar and rough surf, that could be where a rip current may occur.  Further, an active rip current will have a foamy and turbulent appearance as compared to the rest of the tidal activity around it.  If you find yourself caught in a rip current, don’t fight it; allow it to pull you all the way out and then swim parallel to the shore. Even the strongest swimmer can’t swim back to shore amid a rip current. Most importantly, don’t panic. Understanding the aspects of a rip current is the best way to avoid panic.

Courtesy of Katie Thomas

Speaking of crashing waves, have you ever wondered why waves break at certain points along the surf? The key to understanding why waves break is connected to the height of the wave, the depth of the water beneath it, the gradient or slope of the beach and the energy of the wave. A wave starts to crash when the ocean depth decreases to half of the wave’s wavelength. When this occurs the wave begins to touch the bottom of the ocean floor.  Water molecules begin to scape across the ocean floor, causing drag or friction and the wave’s energy begins to decrease, thus the wave grows upward increasing the wave height. As the wave continues to drag along the ocean floor, friction slows the bottom of the wave down as the top of the wave rushes ahead leaning forward until it tumbles over and crashes on shore. 

As you can now see there is so much more occurring at the beach than you may have first thought. Weather at the coast is very dynamic and often changing by the hour. One thing you can count on is when to expect high and low tides. Local surf shops and apps have tide tables for specific locations.  Be sure to check those out! Now that you know a little bit more about natural phenomenon along the coasts, enjoy your summer vacation at the beach and as you stand at the waters edge you will be much more aware of all the weather and ocean activity that is happening right in front of you!

-Katie