The Great Circulation: Global Wind Belts

If the Sun heats the equator more directly than the poles, then warm air rises at the equator and cool air sinks at the poles. If this movement is combined with the rotation of the Earth, then the air is diverted into the distinct patterns we call global wind belts.

If the Earth were stationary, air would move in a straight line from high to low pressure. If the Earth rotates, then the ground beneath the moving air moves at different speeds depending on the latitude, causing the path of the wind to curve. Therefore, the rotation is the direct cause of the Coriolis Effect.

If air sinks at 30 degrees and moves back toward the low pressure at the equator, then it creates a steady wind pattern. If these winds were historically used by sailors to move merchant ships across the ocean, then they are identified as the Trade Winds.

If the Earth rotates toward the East, then an object moving toward the North Pole is moving from a faster-spinning part of the Earth to a slower-spinning part. If the object maintains its faster eastward speed as it moves North, then it will pull ahead of the ground below it, resulting in a curve to the right.

If we categorize wind patterns that cover the entire planet based on their latitude, then we find three distinct loops in each hemisphere. If these are the tropical winds (Trade Winds), the mid-latitude winds (Westerlies), and the high-latitude winds (Polar Easterlies), then they are the three primary global wind belts.

If warm air is constantly rising at the equator, then there is very little horizontal wind movement at the surface. If sailors in the past became "stuck" in this region because their sails couldn't catch a breeze, then they named this area of calm the Doldrums.

If wind is named after the direction from which it originates, then a "Westerly" must come from the West. If these winds move air from the subtropical high-pressure zones toward the higher latitudes in a west-to-east direction, then the name is accurate and the statement is true.

If a force appears to deflect moving objects when they are viewed in a rotating reference frame, then that is a specific physical phenomenon. If this phenomenon is what forces the global wind belts to move diagonally rather than north-south, then it is the Coriolis Effect.

If the temperature at the poles is extremely low, then the air molecules move slowly and pack tightly together. If dense, heavy air sinks toward the surface, then it creates a zone of high pressure. Therefore, the cold temperature is the reason for high pressure at the poles.

If air rises at 60 degrees and sinks at 30 degrees, it creates a circulation cell in the mid-latitudes. If the Coriolis Effect curves this moving air so that it flows predominantly from the west, then these global wind belts are identified as the Westerlies.

If air from the tropics cools and sinks at 30 degrees latitude, then it creates a zone of high pressure. If sinking air moves downward instead of sideways at the surface, then the horizontal winds will be very weak. This matches the description of the Horse Latitudes.

If we name the three major atmospheric circulation cells, the one closest to the equator is the most prominent. If this cell involves air rising at the equator and sinking at the subtropics, then it is scientifically known as the Hadley Cell.

If the Earth is a sphere, then the equator has the largest circumference and must travel the furthest distance in 24 hours. If the poles are just points at the axis of rotation, they travel almost no distance in 24 hours. Therefore, the rotational speed in miles-per-hour must decrease as you move away from the equator.

If the Earth is a sphere (E) and rotates (A), then the circumference at the equator is much larger than at the poles. If the circumference is larger, then the equator must move faster (C) to complete a rotation in one day. These three factors combined cause the deflection of the wind.

If these winds originate from the high-pressure zones at the poles and move toward the lower pressure at 60 degrees latitude, they are curved by the Coriolis Effect. If this curve makes them come from the east, then they are called Easterlies. Therefore, the statement is true.

If air is moving from the North or South Pole toward the mid-latitudes, it is moving cold air from a high-pressure zone to a lower-pressure zone. If the Coriolis Effect curves this wind from the east, then the resulting global wind belts are the Polar Easterlies.

If the Trade Winds blow consistently toward the west in the tropics and the Westerlies blow toward the east in the mid-latitudes, then sailors can plan routes using these winds. If following these "belts" allowed ships to cross the Atlantic and return home efficiently, then they acted as natural transportation highways.

If there is a large temperature and pressure difference between two global wind belts (like the Westerlies and the Polar Easterlies), then a strong pressure gradient is formed at high altitudes. If this gradient causes air to move at very high speeds, then it forms the narrow band of wind known as a Jet Stream.

If wind is defined as the movement of air to balance out pressure differences, then the force must push from the area of higher concentration to the area of lower concentration. If this is the fundamental rule for all air movement on Earth, then it applies to the wind belts as well.

If the Sun heats the Earth unevenly and the Earth's rotation curves the resulting air movement, then the patterns created will be large-scale and long-lasting. If these patterns are found in the same latitudes year after year, then they are the permanent global wind belts.