GKites: Wind Origins
The trade winds are most regular winds of all kinds on earth. The trade winds meet at the doldrums. You can visualize more about trade winds & Hadley Cells in this animation: These polar cold winds converge with the warm easterlies near 60° latitudes and form the Polar front or Mid Latitude front. Where the polar easterlies meet warm air from the westerlies, a stormy region known as a front forms. Although the area that receives direct sunlight can shift by up to 46 º north and south of the . As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for. The boundary between these two areas is called a front. Areas where prevailing winds meet are called convergence zones. (In the Southern Hemisphere, low-pressure systems will be on your right.) Ships relied on trade winds to establish quick, reliable routes across the vast Atlantic and, later, Pacific .
As the temperature of the surface of the land rises, the land heats the air above it.
Global Winds: Trade Winds, Westerlies and Polar Easterlies
The warm air is less dense and so it rises. This rising air over the land lowers the sea level pressure by about 0. The cooler air above the sea, now with higher sea level pressure, flows towards the land into the lower pressure, creating a cooler breeze near the coast. The strength of the sea breeze is directly proportional to the temperature difference between the land mass and the sea. At night, the land cools off more quickly than the ocean due to differences in their specific heat values, which forces the daytime sea breeze to dissipate.
Global Wind Circulations
If the temperature onshore cools below the temperature offshore, the pressure over the water will be lower than that of the land, establishing a land breeze, as long as an onshore wind is not strong enough to oppose it. The wind flows towards a mountain and produces a first oscillation A. A second wave occurs further away and higher. The lenticular clouds form at the peak of the waves B. Over elevated surfaces, heating of the ground exceeds the heating of the surrounding air at the same altitude above sea level, creating an associated thermal low over the terrain and enhancing any lows which would have otherwise existed,   and changing the wind circulation of the region.
In areas where there is rugged topography that significantly interrupts the environmental wind flow, the wind can change direction and accelerate parallel to the wind obstruction.
In what stormy region do the westerlies and polar easterlies converge
Jagged terrain combines to produce unpredictable flow patterns and turbulence, such as rotors. Strong updraftsdowndrafts and eddies develop as the air flows over hills and down valleys. Wind direction changes due to the contour of the land. If there is a pass in the mountain range, winds will rush through the pass with considerable speed due to the Bernoulli principle that describes an inverse relationship between speed and pressure.
Global Wind Circulations
The airflow can remain turbulent and erratic for some distance downwind into the flatter countryside. Mid-latitude Cyclones At mid-latitudes, such as Canada, there is not a strong vertical circulation cell. Instead, the winds create large, horizontally swirling low- and high-pressure systems that we see on weather maps see figure below. High-pressure regions, called anticyclones, are associated with fair weather, clear skies, but light winds not good for sailing.
Low-pressure regions, called extratropical cyclones, are associated with fronts, bad weather, and strong winds not good for pleasure sailing. Often the best sailing at mid latitudes is in between the highs and lows, where the winds are moderate and weather is still OK. The Coriolis effect causes winds rotating counterclockwise around lows in the N. Hemisphere, and clockwise around highs. These circulations are superimposed by a general west-to-east movement of all the air at mid-latitudes.
Winds are named by where they come from. At mid-latitudes is a general west-to-east air flow known as the Westerlies. Mid-latitude cyclones Lows and anticyclones Highs are imbedded in a general westerly flow; hence, these weather systems usually move from west to east.
The westerlies are generally stronger in the Southern Hemisphere because they flow over water. The westerlies in both hemispheres are stronger in winter than in summer. Surface winds around the globe, as is useful for trans-oceanic sailing.
- Learning Goals 9a:
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- Hadley cell
L and H indicate low and high pressure. The air movements here are much weaker compared to those in the Hadley cells. The cool polar air meets the warmer mid-latitude air near the 60th parallel where it rises.
This zone is known as the polar front. Here, winds blow from the east and north, shifting slightly east due to the Coriolis effect and are called the polar easterlies.
Summary Near the earth's surface at mid-latitudes such as the latitude of southern Canada the prevailing winds are from the west. These winds are called westerlies. Embedded within this general flow are extra-tropical cyclones lows that are also blown from west to east by the prevailing winds. But near these lows and their associated fronts, the local winds can deviate from westerly - - the winds blow counterclockwise in the N. Hemisphere around the low-pressure center.
Also embedded in the mid-latitude flow are moving anticyclones highs that are also blown from west to east. But near these highs, the winds rotation clockwise around the high center in the N. Winds rotation in opposite directions around highs and lows in the S. Near the earth's surface at tropical low latitudes, the prevailing wind is from the east.