What is the difference between prevailing westerlies and polar easterlies

The Hadley Cell is what creates monsoon climates in sub-tropical regions. Polar easterlies occur between the poles and 60 degrees latitude in both hemispheres. Prevailing westerlies - In the middle latitudes of the Earth, between 35 and 65 degrees latitude, are the prevailing westerly winds. This is between 30 o N and 60 o N and 30 o S and 60 o S respectively. Polar Front: Between the polar easterlies and the westerlies is the polar front. At the surface these winds are called westerlies and the cell is known as the Ferrel cell.

Trade winds occur from 30 degrees North latitude and 30 degrees South latitude. The tropical easterly trade winds blow hemispheric air into the Hadley Cell, which is dominated by hot air rising to form clouds and precipitation.

Sailors noticed the stillness of the rising and not blowing air near the equator and gave the region the depressing name "doldrums. Chemistry, They change their directions. Trade winds and westerlies.

Example: Trade winds, westerlies, easterlies. Trade Winds. See circulation index , high index , low index ; 30 seconds. These winds are often grouped together as trade winds , easterlies, and westerlies. Polar Easterlies: From degrees latitude, the Polar easterlies blow irregularly from the east and north. Many depressions form as waves on the inter-anticyclonic fronts, which move southeastward into the belt of the westerlies.

As nouns the difference between tradewinds and westerlies. What is the relative difference between the length of day and night for each of the seasons in each hemisphere? They originate from the high-pressure areas in the horse latitudes and trend towards the poles and steer extratropical cyclones in this general manner. Trade winds occur between 30 degrees latitude and the equator in both hemispheres.

Polar Easterlies. Permanent winds: They blow all around the year, that too in a specific direction. Are trade winds warm or cold? There is a relationship between long-rains rainfall and the number of days spent influenced by different airmasses Figure 6. The polar easterlies.

The difference between the land and sea temperatures cause the pressure belts of the of the primary wind circulation to be broken up into enclosed high- and low-pressure areas, called centers of action.

However, when the winds travel over water, the westerlies tend to reach higher speeds to that of on land. What weather are you about to experience? The boundary between these two areas is called a front. It is an area where to Low Pressures meet and it results in very little wind. The Ferrel cell is located between the Hadley and polar circulation cells Fig.

Thus, the Ferrel cell is like an atmospheric gear driven by the Hadley and polar circulation cells. In the Ferrel cell in the Northern Hemisphere, the surface winds blow from the southwest and are called the prevailing westerlies. The prevailing westerlies blow from the southwest to the northeast because of the Coriolis effect—the air mass is moving faster than the rotational speed of the land and water beneath. Prevailing westerlies are the dominant winds blowing across most of the continental United States.

The areas where the circulation cells come together have no steady prevailing winds. At the intertropical convergence zone near the equator Fig. The doldrums are an area of low pressure around the equator, where prevailing winds are calm.

Because of the lack of winds in the doldrums, sailing vessels had a difficult time crossing the equator. The term originates from a time when sailing ships could not make headway without steady wind, and the horses held aboard would die from lack of food and water. Another explanation is that sailors who were paid for part of their work before a voyage spent all of that pay at once, going into debt.

The three-cell model Fig. The actual global air distribution is much more complex. One of the reasons for this complexity is because water and land heat and cool differently. The amount of water and land area is different in the Northern and Southern Hemispheres. Another reason air currents are complex is that the locations of high- and low-pressure systems change dramatically with the seasons. In addition, high- and low-pressure systems do not typically form uniform bands, as described earlier.

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Near the equator, the trade winds converge into a broad east to west area of light winds. The area is known as the doldrums because there are light winds. This area is known as the intertropical convergence zone ITCZ , and is the area with the most active weather. As you learned the Northern Hemisphere has more landmass and is relatively warmer than the Southern Hemisphere.

Also at the equator, warmer, moist air rises and produces a low-pressure area extending many kilometers north and south of the equator. Here the sky is clear. There are few clouds and little rainfall. Polar Easterlies Polar easterlies are dry, cold prevailing winds that blow from the east. They emanate from the polar high s, areas of high pressure around the North and South Poles.

Polar easterlies flow to low-pressure areas in sub-polar regions. Westerlies Westerlies are prevailing winds that blow from the west at midlatitude s. They are fed by polar easterlies and winds from the high-pressure horse latitudes, which sandwich them on either side. 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.

Throughout the Roaring Forties, there are few landmasses to slow winds. 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. 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.

Westerlies have an enormous impact on ocean current s, especially in the Southern Hemisphere. Driven by westerlies, the powerful Antarctic Circumpolar Current ACC rushes around the continent from west to east at about 4 kilometers per hour 2. The ACC is the largest ocean current in the world, and is responsible for transporting enormous volumes of cold, nutrient-rich water to the ocean, creating healthy marine ecosystems and food webs. Horse Latitudes The horse latitude s are a narrow zone of warm, dry climate s between westerlies and the trade winds.

Horse latitudes are about 30 and 35 degrees north and south. Many deserts, from the rainless Atacama of South America to the arid Kalahari of Africa, are part of the horse latitudes. The prevailing winds at the horse latitudes vary, but are usually light. Even strong winds are often short in duration. Trade Winds Trade wind s are the powerful prevailing winds that blow from the east across the tropics. Trade winds are generally very predictable. They have been instrumental in the history of exploration, communication, and trade.

Ships relied on trade winds to establish quick, reliable route s across the vast Atlantic and, later, Pacific Oceans. Even today, shipping depends on trade winds and the ocean currents they drive. In , Norwegian explorer Thor Hyerdahl and a small crew used trade winds to travel from the coast of Peru to the coral reefs of French Polynesia, more than 6, kilometers 4, miles , in a sail-powered raft. The expedition, named after the raft Kon-Tiki aimed to prove that ancient mariners could have used predictable trade winds to explore wide stretches of the Pacific.

Trade winds that form over land called continental trade winds are warmer and drier than those that form over the ocean maritime trade winds. The relationship between continental and maritime trade winds can be violent. Most tropical storm s, including hurricanes, cyclones, and typhoons, develop as trade winds.

Differences in air pressure over the ocean cause these storms to develop. As the dense, moist winds of the storm encounter the drier winds of the coast, the storm can increase in intensity. Strong trade winds are associated with a lack of precipitation , while weak trade winds carry rainfall far inland. The most famous rain pattern in the world, the Southeast Asian monsoon, is a seasonal, moisture-laden trade wind.

Besides ships and rainfall, trade winds can also carry particles of dust and sand for thousands of kilometers. Particles from Saharan sand and dust storms can blow across islands in the Caribbean Sea and the U.

Dust storms in the tropics can be devastating for the local community. Valuable topsoil is blown away and visibility can drop to almost zero. Across the ocean, dust makes the sky hazy. These dust storms are often associated with dry, low-pressure areas and a lack of tropical storms. Doldrums The place where trade winds of the two hemispheres meet is called the intertropical convergence zone ITCZ. The area around the ITCZ is called the doldrums.

Prevailing winds in the doldrums are very weak, and the weather is unusually calm. In fact, the low-pressure doldrums are created as the sun heats the equatorial region and causes air masses to rise and travel north and south. This warm, low-pressure equatorial wind descends again around the horse latitudes.

Some equatorial air masses return to the doldrums as trade winds, while others circulate in the other direction as westerlies. Although monsoons impact tropical as well as equatorial regions, the wind itself is created as the ITCZ moves slightly away from the Equator each season. This change in the doldrums disturbs the usual air pressure, creating the moisture-laden Southeast Asian monsoon.

Results of Wind Wind traveling at different speeds, different altitudes, and over water or land can cause different types of patterns and storms. Jet Streams Jet stream s are geostrophic winds that form near the boundaries of air masses with different temperatures and humidity. The rotation of the Earth and its uneven heating by the sun also contribute to the formation of high-altitude jet streams.

These strong, fast winds in the upper atmosphere can blow kph mph. There is little turbulence in the stratosphere, which is why commercial airline pilots like to fly in this layer. Riding with jet streams saves time and fuel. Have you ever heard someone talk about a headwind or tailwind when they are talking about airplanes? These are jet streams. If they are behind the plane, pushing it forward, they are called tailwind s.

They can help you get to your destination more quickly. If the winds are in front of the plane, pushing it back, they are called headwind s. Strong headwinds can cause flight delays. Hurricane A hurricane is a giant, spiraling tropical storm that can pack wind speeds of over kph mph and unleash more than 9 trillion liters 2. These same tropical storms are known as hurricanes in the Atlantic Ocean, cyclone s in the northern Indian Ocean, and typhoon s in the western Pacific Ocean.

These tropical storms have a spiral shape. The spiral swirling counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere develops as a high-pressure area twists around a low-pressure area. Wind conditions that can lead to hurricanes are called tropical disturbances.

They begin in warm ocean waters when the surface temperatures are at least If the disturbance lasts for more than 24 hours and gets to speeds of 61 kph 38 mph , it becomes known as a tropical depression. When a tropical depression speeds up to kph mph , it is known as a tropical storm, and is given a name.

Meteorologist s name the storms in alphabetical order, and alternate with female and male names. When a storm reaches kph 74 mph , it becomes a hurricane and is rated from 1 to 5 in severity on the Saffir Simpson scale. A Category 5 hurricane is the strongest storm possible on the Saffir-Simpson scale. Winds of a Category 5 blow at kph mph. Hurricane Ethel, the strongest hurricane in recorded history, roared across the Gulf of Mexico in September Winds were sustained at kph mph.

However, Hurricane Ethel quickly dissipate d. Although its winds ultimately blew as far north as the U. Hurricanes bring destruction to coastal ecosystems and communities. When a hurricane reaches land, it often produces waves that can reach 6 meters 20 feet high and be pushed by high winds kilometers miles inland. These storm surge s are extremely dangerous and cause 90 percent of all hurricane deaths.

The deadliest hurricane on record is the Great Hurricane of Although sophisticated meteorological equipment was not available at that time, winds may have reached kph mph as the hurricane hit Barbados and other islands in the Caribbean Sea. This may have been enough to strip the bark from trees. More than 20, people died as a result of the hurricane as it made its way across Barbados, St. Although it decreased in intensity, the hurricane was tracked through the U.

Hurricanes can be destructive in other ways. High winds can create tornadoes. Heavy rains contribute to floods and landslides, which may occur many kilometers inland. Damage to homes, businesses, schools, hospitals, roads, and transportation systems can devastate communities and entire regions.

Hurricane Katrina, which blew through the Gulf of Mexico and into the southern U. New Orleans, Louisiana, was almost completely devastated by Hurricane Katrina. New Orleans, as well as Mobile, Alabama, and Gulfport, Mississippi, took years to recover from the damage done to their structures and infrastructure.

The best defense against a hurricane is an accurate forecast that gives people time to get out of its way. The National Hurricane Center issues hurricane watches for storms that may endanger communities, and hurricane warnings for storms that will reach land within 24 hours.