![]() ![]() Westerlies have an enormous impact on ocean currents, especially in the Southern Hemisphere. The westerlies of the Roaring Forties were very important to sailors during the Age of Exploration, when explorers and traders from Europe and western Asia used the strong winds to reach the spice markets of Southeast Asia and Australia. The tip of South America and Australia, as well as the islands of New Zealand, are the only large landmasses to penetrate the Roaring Forties. Throughout the Roaring Forties, there are few landmasses to slow winds. The strongest westerlies blow through the “Roaring Forties,” a wind zone between 40 and 50 degrees latitude in the Southern Hemisphere. Westerlies are strongest in the winter, when pressure over the pole is low, and weakest in summer, when the polar high creates stronger polar easterlies. They are fed by polar easterlies and winds from the high-pressure horse latitudes, which sandwich them on either side. Westerlies Westerlies are prevailing winds that blow from the west at midlatitudes. Polar easterlies flow to low-pressure areas in sub-polar regions. They emanate from the polar highs, areas of high pressure around the North and South Poles. Polar Easterlies Polar easterlies are dry, cold prevailing winds that blow from the east. (In the Southern Hemisphere, low-pressure systems will be on your right.) Wind Zones The Earth contains five major wind zones: polar easterlies, westerlies, horse latitudes, trade winds, and the doldrums. In 1857, Dutch meteorologist Christoph Buys Ballot formulated a law about geostrophic winds: When you stand with your back to the wind in the Northern Hemisphere, low pressure is always to your left. The Coriolis effect causes some winds to travel along the edges of the high-pressure and low-pressure systems. The Coriolis effect makes wind systems twist counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. This happens because Earth’s rotation generates what is known as the Coriolis effect. Generally, prevailing winds blow east-west rather than north-south. Areas where prevailing winds meet are called convergence zones. Prevailing winds are winds that blow from a single direction over a specific area of the Earth. The complex relationships between fronts cause different types of wind and weather patterns. The boundary between these two areas is called a front. Winds generally blow from high-pressure areas to low-pressure areas. At the same time, cooler, denser air moves over Earth’s surface toward the Equator to replace the heated air. Warm equatorial air rises higher into the atmosphere and migrates toward the poles. ![]() At the Equator, the sun warms the water and land more than it does the rest of the globe. Differences in atmospheric pressure generate winds. Landforms, processes, and impacts of wind are called Aeolian landforms, such as sand dunes and Loess deposits, which are deposits of silt. It is the great equalizer of the atmosphere, transporting heat, moisture, pollutants, and dust great distances around the globe. It is strong enough to carry sailing ships across the ocean and rip huge trees from the ground. It can dry your clothes in summer and chill you to the bone in winter. It does not have much substance-you cannot see it or hold it-but you can feel its force. Liu, Qinghua Ye, Shiqiang Wu, M.J.F.Wind is the movement of air caused by the uneven heating of the Earth by the sun. Water age is proved to be an effective indicator of water exchange efficiency, which may help decision-makers to carry out integrated water management at a complex basin scale. Wind speed decline, such as that induced by climate change, has negative effects on both internal and external nutrient source release, and results in water quality deterioration. Water age decreases with higher inflow discharge from tributaries however, discharge effects are less significant than that of wind. Changes in wind direction lead to changes in both the average value and spatial pattern of water age, while the impact of wind speed differs in each tributary group. A well-calibrated and validated three-dimensional Delft3D model is used to investigate both spatial and temporal heterogeneity of water age. For each group, the water age has been computed accordingly. On the base of sub-basins of upstream catchments and boundary conditions of the lake, multiple inflow tributaries are categorized into three groups. In this study, water age is used to investigate the impacts of tributary discharge and wind influence on nutrient status in Taihu Lake, quantitatively. (TU Delft Coastal Engineering)Īs the third largest fresh water lake in China, Taihu Lake is suffering from serious eutrophication, where nutrient loading from tributary and surrounding river networks is one of the main contributors. Wu, Shiqiang (Nanjing Hydraulic Research Institute) Wind effects on the water age in a large shallow lake ![]()
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