#Ocean waves pictures websites series#

Likewise, cold air from the poles sinks and moves towards the equator. The hot air over the equator rises and moves away from the equator. This uneven distribution of heat causes air to move. The Sun’s radiation is strongest at the equator and dissipates the closer you get to the poles. These wind patterns (convection cells) are created by radiation from the Sun beating down on Earth and generating heat. Surface ocean currents are driven by consistent wind patterns that persist throughout time over the entire globe, such as the jet stream.

When air moves across the ocean’s surface, it pulls the top layers of water with it through friction, the force of resistance between two touching materials moving over one another. Wind is a major force in propelling water across the globe in surface currents. Gravity pulls the water away from hills and toward valleys and Earth’s rotation steers the moving water. The Sun’s radiation creates prevailing wind patterns, which push ocean water to bunch in hills and valleys. (John James Wild, 1877)Īt the surface, currents are mainly driven by four factors-wind, the Sun’s radiation, gravity, and Earth’s rotation. This is a map ocean surface currents from 1877. Climate change is altering the processes that propel water across the globe, and should this alter ocean currents, it would likely lead to a cascade of even more change. While the ocean as we know it has been in existence since the beginning of humanity, the familiar currents that help stabilize our climate may now be threatened. This planetary movement has a strong effect on how oceans move. Though it appears we live on a stable and stationary planet, we are, in fact, whipping through space around the Sun in an orbit and spinning on an axis. It also requires a shift in perspective to encompass the movement of planets, the Moon, and the Sun.

Ocean motion is influenced by occurrences here on Earth that are familiar, like heat changes and wind. Friction, drag, and density all come into play when describing the nature of a wave, the movement of a current, or the ebb of a tide. Ocean movement is created by the governing principles of physics and chemistry. Water is propelled around the globe in sweeping currents, waves transfer energy across entire ocean basins, and tides reliably flood and ebb every single day. But this is far from the truth-the ocean is constantly in motion. The gravitational pull of the sun and moon also cause waves to form – these are known as tides.Looking toward the sea from land, it may appear that the ocean is a stagnant place.

#Ocean waves pictures websites series#

Seismic activity can cause a series of long-wavelength waves known as a tsunami, due to the displacement of large amounts of water. Not all waves are caused by the wind though. Some research suggests that extreme waves are becoming more likely as a result of climate change, due to an increase in storms and melting of polar ice. The complex forces that give rise to them are now better understood, raising the possibility of rogue wave forecasts in the future. However, through better monitoring of the seas, we now know these freak waves are surprisingly common.

These rogue waves were once thought to be fictional, or vanishingly rare. Occasionally waves merge to form one that is far higher than those surrounding it. But if it blew for 48 hours, the wave’s crest would increase to 10.5 metres, about twice the height of a double-decker bus. Wind blowing for an hour at a speed of 55.6 kilometres per hour over a stretch of water 1000km wide would generate waves with a significant wave height of 0.7 metres. Oceanographers measure wave height using a term called “significant wave height”, which is the average height of the largest 33 per cent of waves in that region of ocean at the time. The height of a wave is determined by the wind strength, the length of time it blows and its fetch – the distance it travels over the water. This causes the wave to stand up then pitch forward before eventually breaking. An analogy is a crowd of people doing a Mexican wave in a stadium: they stay in the same location, but the wave they create travels around the arena.Īs waves reach the shore, the shallow floor begins to run into their base, slowing their deeper parts. The rise and fall of water molecules creates a wave that moves in the direction of the wind. Waves occur when the force of the wind blows over surface water, transferring its energy and causing the water to move in a circular motion. They are mainly caused by winds, and, if unimpeded, can travel for thousands of kilometres. There are many types of waves flowing across the oceans, from small ripples to huge walls of water, 30 metres high peak-to-trough.