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The region of Earth receiving the Sun’s direct rays is the equator. Here, air is heated and rises, leaving low pressure areas behind. Moving to about thirty degrees north and south of the equator, the warm air from the equator begins to cool and sink. Between thirty degrees latitude and the equator, most of the cooling sinking air moves back to the equator. The rest of the air flows toward the poles. The air movements toward the equator are called trade winds- warm, steady breezes that blow almost continuously. The Coriolis Effect makes the trade winds appear to be curving to the west, whether they are traveling to the equator from the south or north.
The trade winds coming from the south and the north meet near the equator. These converging trade winds produce general upward winds as they are heated, so there are no steady surface winds. This area of calm is called the doldrums.
Between thirty and sixty degrees latitude, the winds that move toward the poles appear to curve to the east. Because winds are named from the direction in which they originate, these winds are called prevailing westerlies. Prevailing westerlies in the Northern Hemisphere are responsible for many of the weather movements across the United States and Canada.
At about sixty degrees latitude in both hemispheres, the prevailing westerlies join with polar easterlies to reduce upward motion. The polar easterlies form when the atmosphere over the poles cools. This cool air then sinks and spreads over the surface. As the air flows away from the poles, it is turned to the west by the Coriolis effect. Again, because these winds begin in the east, they are called easterlies. Many of these changes in wind direction are hard to visualize. Complete this exercise to see the pattern of the winds.
Materials Needed
* illustration below
* pencil
* colored pencil or markers
Illustration of the earth needed for the experiment.
Procedure
Carefully read the paragraphs above. Draw arrows to represent wind movement, be sure to show how winds change direction at certain latitudes, which are labeled for you. Arrows representing the trade winds have already been drawn. Use orange to color the trade winds, green for the prevailing westerlies, and blue for the polar easterlies. You may need to look back at the results of Blow, Wind, Blow to be able to show the Coriolis effect.
Questions
1. What winds would Columbus have used to travel from Spain to the Caribbean?
2. Which winds would he have needed to return to Europe?
3. Would winds have favored European explorers seeking to travel east around the tip of Africa?
Global Winds
Earth’s curved surface causes some parts of Earth to receive the
Sun’s rays more directly than other parts. For example, the Sun
shines more directly on the surface at the equator than at the
poles. As the warmer air over the equator rises, colder air from
the poles rushes toward the equator to take its place. This steady
exchange of warm and cold air that occurs between the equator
and the poles produces global wind belts. Earth’s rotation causes
the direction of the winds to bend slightly: toward the right in
the Northern Hemisphere and toward the left in the Southern
Hemisphere. Global winds push air masses around Earth and
bring changes in the weather. In the United States, global winds
called the prevailing westerlies push air masses from west to east.
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The water of the ocean surface moves in a regular pattern called surface ocean currents.
The water at the ocean surface is moved primarily by winds that blow in certain patterns because of the Earth’s spin and the Coriolis Effect. Winds are able to move the top 400 meters of the ocean creating surface ocean currents.
paragraph from http://www.windows.ucar.edu/tour/link=/…/ocean_currents.html
Weather forecasts are made by collecting as much data as possible about the current state of the atmosphere (particularly the temperature, humidity and wind) and using understanding of atmospheric processes (through meteorology) to determine how the atmosphere evolves in the future.
wikipedia.com
wind is made by low pressure and high pressure
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One of the primary goals of physical oceanography is to know the average movement of ocean water, everywhere around the globe. Besides knowing the average flow, it is also very useful to know how much this flow can change over a course of a day, over a year, over ten years, and longer. Ocean currents are organized flows that persist over some geographical region and over some time period such that water is transported from one part of the ocean to another part of the ocean. Currents also transport plankton, fish, heat, momentum, and chemicals such as salts, oxygen, and carbon dioxide. Currents are a significant component of the global biogeochemical and hydrological cycles. Knowledge of ocean currents is also extremely important for marine operations involving navigation, search and rescue at sea, and the dispersal of pollutants.
It is quite evident from observations of ocean flow that the wind moves water, and that the wind is one of the primary forces that drive ocean currents. In the early part of the 20th century, a Norwegian scientist, Fridtjof Nanson, noted that icebergs in the North Atlantic moved to the right of the wind. His student, V. Walfrid Ekman, demonstrated that the earth’s rotation caused this effect and in particular, that the Coriolis force was responsible and in the Southern Hemisphere, it causes water to move to the left of the wind. One of the primary results of Ekman dynamics is that the net movement of water, forced by large-scale winds, are to the right (left) of the wind in the Northern (Southern) Hemisphere. This is a surprising result since one would guess that water moves in the direction of the wind, and a quick glance at wind and current data would also indicate this. For example, the Gulf Stream flows eastward, in the direction of the overlying westerly winds (winds flowing from west to east). However, the story is more complicated than this.
Winds accelerate (near-)surface fluid particles by imparting momentum to the fluid through surface stresses. At first, particles move in the direction of the wind. As time goes on, the earth’s rotation deflects the particles to the right/left in the Northern/Southern hemispheres, respectively. The large-scale mass field adjusts so that there is an approximate geostrophic balance between the pressure gradient force and the Coriolis acceleration.
The Jet Stream map shows today’s high wind speed levels and jetstream directions. Jet streams are fast flowing, relatively narrow air currents found in the atmosphere around 10 kilometers above the surface of the Earth. They form at the boundaries of adjacent air masses with significant differences in temperature, such as the polar region and the warmer air to the south. The jet stream is mainly found in the tropopause, at the transition between the troposphere (where temperature decreases with height) and the stratosphere (where temperature increases with height).
The water at the ocean surface is moved primarily by winds that blow in certain patterns because of the Earth’s spin and the Coriolis Effect. Winds are able to move the top 400 meters of the ocean creating surface ocean currents.
Surface ocean currents form large circular patterns called gyres. Gyres flow clockwise in Northern Hemisphere oceans and counterclockwise in Southern Hemisphere oceans because of the Coriolis Effect. creating surface ocean currents. Near the Earth’s poles, gyres tend to flow in the opposite direction
The Florida current can be considered the “official” beginning of the Gulf Stream System. It is defined here as that section of the system which stretches from the Florida Straits up to Cape Hatteras. The Florida Current was first reported by the Spanish explorer Ponce de Leon in 1513 when he discovered Florida, (Galstoff, 1954) The Florida Current receives its water from two main sources, the Loop Current and the Antilles Current. The Loop current is the most significant of these sources and can be considered the upstream extension of the Gulf Stream System.
The Florida Current has been shown to have a mean transport of about 30 Sv in historical literature (Schmitz and Richardson, 1968; Niiler and Richardson, 1973). This value has been confirmed in numerous studies and has stood up to modern scrutiny. More recently the STACS study confirmed this value with the finding a mean transport of 31.5 Sv at 27°N in the straits of Florida (Molinari et al., 1985; Leaman et al., 1987; Schott et al., 1988; Lee et al 1985; Larsen and Sanford, 1985). Researchers used undersea cables, current meter moorings and a Pegasus profiler, and all three methods produced transports that were within 1-2 Sv of each other. There has however, been demonstrated that this current is subject to both seasonal and interannual variability. These changes are significant and can amount to as much as a 10 Sv difference between high and low values along the eastern Florida coast (Schott et al. 1988). Most of this water appears to originate in the Gulf of Mexico. Early estimates of inflow through island passages in the Florida Straits are only about 3.5 Sv. (Schmitz and Richardson, 1968) Later estimates are much larger with Schmitz and Richardson (1990) reporting a total of 28.8 Sv for five key passages, Grenada, St. Vincent, St. Lucia, Dominica and Windward. Wilson and Johns (1996) found an influx of 17.5 Sv and note the presence of strong outflows in these passages as well. Flow through these passages is highly variable and may in part account for the considerable variability of the Florida Current.
Fronts are zones of difference between two different air masses. The type of front depends on both the direction in which the air mass is moving and the characteristics of the air mass. There are four types of fronts: cold front, warm front, stationary front, and occluded front. Cold front is a front in which cold air is replacing warm air at the surface. Cold fronts tend to move the farthest and tend to be associated with the most violent weather among all types of fronts. Cold fronts tend to move faster than all other types of fronts. Warm front is a front in which warm air replaces cooler air at the surface. Warm fronts tend to move slowly and warm fronts are typically less violent than cold fronts. They can trigger thunderstorms, but haven’t really been associated with heavy weather. Stationary front- a front that does not move or barely moves ,and stationary fronts behave like warm fronts.
The region of Earth receiving the Sun’s direct rays is the equator. Here, air is heated and rises, leaving low pressure areas behind. Moving to about thirty degrees north and south of the equator, the warm air from the equator begins to cool and sink. Between thirty degrees latitude and the equator, most of the cooling sinking air moves back to the equator. The rest of the air flows toward the poles. The air movements toward the equator are called trade winds- warm, steady breezes that blow almost continuously. The Coriolis Effect makes the trade winds appear to be curving to the west, whether they are traveling to the equator from the south or north.
The trade winds coming from the south and the north meet near the equator. These converging trade winds produce general upward winds as they are heated, so there are no steady surface winds. This area of calm is called the doldrums.
Between thirty and sixty degrees latitude, the winds that move toward the poles appear to curve to the east. Because winds are named from the direction in which they originate, these winds are called prevailing westerlies. Prevailing westerlies in the Northern Hemisphere are responsible for many of the weather movements across the United States and Canada.
At about sixty degrees latitude in both hemispheres, the prevailing westerlies join with polar easterlies to reduce upward motion. The polar easterlies form when the atmosphere over the poles cools. This cool air then sinks and spreads over the surface. As the air flows away from the poles, it is turned to the west by the Coriolis effect. Again, because these winds begin in the east, they are called easterlies. Many of these changes in wind direction are hard to visualize. Complete this exercise to see the pattern of the winds.
The dominant meanders, determined from current meter data in the Florida Current, have wavelengths of 340 km and 170 km, periods of 12 days and five days, and propagate at 28 km/d and 36 km/d, respectively (Johns and Schott, 1987). The amplitude of the meanders increase outside of the constraint of the Straits of Florida. Meanders and the eddies they generate serve as the principal form of mesoscale variability along the path of the Florida Current within the Mid Atlantic Bight (between Cape Canaveral, Florida and Cape Hatteras, North Carolina). The Florida Current is deflected offshore near 32°N and it’s eddy variability decreases downstream of this deflection (Olson et al., 1983; Vukovich and Crissman, 1978). The deflection of the Florida Current is caused by the presence of a topographic irregularity known as the Charleston Bump near 31°N. This deflection in the path of the current has been shown to be bimodal in character with the Florida Current assuming either a weakly or strongly deflected state. Bane and Dewar (1988) observed that the transition between weakly and strongly deflected modes can occur rapidly, within a few days. The Florida current can remain in the strongly deflected mode for at least several months. They also note that the differing modes are associated with different types of low frequency variation downstream.
The seasonal signal in the Florida Current was discovered in tide gauge measurements by Montgomery (1938) who found evidence for a seasonal maximum in July and minimum in October with secondary maximum and minimum in January and April respectively. Other early reports of this signal include Iselin (1940), Fuglister (1951), Patullo et al. (1955), Wunsch et al. (1969), Schmitze and Richardson (1968) and Niiler and Richardson (1973). Niiler and Richardson (1973) found a winter transport of 25.4 Sv and summer transport of 33.6 and that seasonal changes accounted for about 45% of the variability between historical transport estimates. This supports Wuncsch et al. (1969) who, based on sea level height differences, concluded that the seasonal transport differences were approximately 10% of the annual mean signal. STACS results indicated that transports can vary between 20Sv and 40 Sv (Molinari et al. 1985; Leaman et al. 1987; Schott et al. 1988; Lee et al 1985; Larsen and Sanford, 1985). Recently the annual signal has been attributed to a build up and breakdown of the Bermuda High as it relates to the seasonal cycle with the trade winds. Lee et al. (1996) found a correlation between the observed wind field and observed transport variability confirming the predictions in the numerical model of Boning et al (1991). In addition to the annual signal, there is also a semiannual summer maximum tied to an additional strengthening of the trade winds and increase in local winds (Lee et al. 1996). Historical records have shown that monthly variability within the Florida current can be as high as the seasonal variability There are also short term variations with periods of 2-20 days. These fluctuations are correlated to local winds and are much stronger in summer than in winter (Lee and Williams, 1988).
Global warming is when the earth heats up (the temperature rises). It happens when greenhouse gases (carbon dioxide, water vapor, nitrous oxide, and methane) trap heat and light from the sun in the earth’s atmosphere, which increases the temperature. This hurts many people, animals, and plants. Many cannot take the change, so they die.Greenhouse gasses are gasses are in the earth’s atmosphere that collect heat and light from the sun. With too many greenhouse gasses in the air, the earth’s atmosphere will trap too much heat and the earth will get too hot. As a result people, animals, and plants would die because the heat would be too strong. Many things cause global warming. One thing that causes global warming is electrical pollution. Electricity causes pollution in many ways, some worse than others. In most cases, fossil fuels are burned to create electricity. Fossil fuels are made of dead plants and animals. Some examples of fossil fuels are oil and petroleum. Many pollutants (chemicals that pollute the air, water, and land) are sent into the air when fossil fuels are burned. Some of these chemicals are called greenhouse gasses.
We use these sources of energy much more than the sources that give off less pollution. Petroleum, one of the sources of energy, is used a lot. It is used for transportation, making electricity, and making many other things. Although this source of energy gives off a lot of pollution, it is used for 38% of the United States’ energy.
Some other examples of using energy and polluting the air are: