Waves do not propagate in the same way everywhere in the ocean due to the depth of the water, the shape and relief of the seabed, as well as the strength and direction of the wind that generates them.
Storms, with their powerful winds and sudden changes in atmospheric pressure, generate higher and more energetic waves. When these weather disturbances occur at sea, the waves can travel great distances and form well-defined swells. The stronger and longer a storm lasts, the larger the waves will be. Conversely, in relatively calm weather areas, you will get smaller ripples. The difference in atmospheric pressure also plays a role: a sudden drop can intensify the wave phenomenon. In short, the weather stirs up or calms the ocean's surface according to its mood!
Underwater, waves encounter mountains, valleys, or underwater plateaus, and all of this directly influences their behavior. When waves reach a shallow area, their speed slows down while their height increases: they become larger and can even "break." Conversely, above deeper areas, waves are often less pronounced and more regular. Thus, an underwater cliff or a shoal alters the path and power of the waves on the coast. This phenomenon explains why some renowned surf spots enjoy exceptional conditions due to their unique underwater topography.
The shape and orientation of the coastline completely change the appearance of the approaching waves. Deep and narrow bays often trap wave energy, creating calm swells or gentle rolling waves. Conversely, when a coastline juts out like a point, it concentrates the waves, making them stronger and more powerful. Similarly, a rocky, jagged, or irregular coastline will fragment and reflect the waves, multiplying the directions and creating choppy areas where the water bounces everywhere. On the other hand, an open beach with a gentle slope allows the wave energy to spread out quietly, generating regular and predictable waves, perfect for surfers looking for stable swells.
The wind is the main driver of waves. If the wind blows strong, for a long time, and over a great distance, the waves will tend to become large and powerful. Conversely, if the wind is weak or intermittent, the sea will remain rather calm, with small short waves. Orientation also plays a role: depending on the direction from which the wind blows, the waves will follow more or less the same direction. A wind coming from the land towards the sea rarely creates large waves near the shore. In contrast, a wind coming from the open sea will direct larger waves towards the coast, which are ideal for surfing enthusiasts. Therefore, the combination of wind intensity and direction largely determines the appearance of the sea in a given location.
When waves meet ocean currents, it creates an interaction that can significantly change the game: the speed, height, and even the shape of the waves are altered. A current flowing against the waves causes them to swell, becoming taller, steeper, and sometimes dangerous for navigation. Conversely, when waves and currents move in the same direction, the waves lose height and appear gentler. Sometimes, these interactions create chaotic or complex areas known as rough zones, which are difficult to cross by boat. These encounters between waves and currents partly explain why oceans do not exhibit the same type of swell everywhere.
In certain regions of the world, such as Nazaré in Portugal, the underwater topography significantly amplifies the waves, attracting the best surfers from around the globe in search of records.
The 'rogue waves' or 'monster waves' can suddenly reach two to three times the average height of the surrounding waves, posing a real threat even to large ships.
The speed of wave propagation in the ocean strongly depends on the depth: the deeper the water, the faster the waves move.
Opposing ocean currents to the direction of wave propagation can cause a significant increase in wave height, making certain areas particularly dangerous for navigation.
When waves approach a shore, their direction gradually changes, a phenomenon known as refraction. This occurs because the speed of a wave mainly depends on the depth of the water. Upon reaching shallower waters near the coast, their height increases and their direction is progressively reoriented until it becomes almost parallel to the shoreline.
Yes, the size and power of the waves can vary depending on the seasons, mainly due to changes in wind and atmospheric pressure. For example, in winter, storms are generally more intense, resulting in larger and more powerful waves than in summer.
A calm sea under windy conditions can result from a limited fetch, a short duration of wind blowing, or a wind direction opposite to that of the existing swell, thus reducing the efficiency of energy transfer and preventing the waves from building up.
Some oceanic regions offer particular weather conditions, associated with strong, consistent winds over long distances (fetch). These conditions favor the formation of larger amplitude waves. Conversely, in more sheltered areas or with limited fetch, the waves will generally be less impressive.
The underwater topography plays a crucial role in affecting the speed, height, and direction of waves. A gentle slope creates waves that break gradually, while a steeper profile produces taller and more crashing waves. Obstacles such as reefs or shallows can also fragment or amplify the waves.
Ocean currents can alter the speed and trajectory of waves depending on their orientation. A current flowing in the same direction as the waves amplifies their size, while a current opposing them tends to decrease their wavelength but increases their height, making them steeper and potentially more dangerous.
No one has answered this quiz yet, be the first!' :-)
Question 1/5
