Winds Aloft
Winds Aloft refers to the wind patterns and conditions at high altitude. These can either help or hinder your flights.
How Winds Aloft Are Implemented
The presence of Winds Aloft and Jet Streams has been handled separately, but both effects are controlled by the rotation of the Hadley, Ferrel and Polar cells.
The speed of the jet streams are driven by temperature, location and season. The sub-tropical winter Jet Stream this is the fastest and probably the one of most interest. To represent this scenario a Jet Stream preset has been created as an individual ‘FEW’ weather type.
Winds Aloft are integrated into all of the ‘FEC’ cloud types as moderate high-altitude wind speeds following the core Jet Stream direction but with some variation. These winds are not inside the Jet Streams themselves but can be quite close without picking up the core jet stream speed.
How Winds Aloft Are Created
Winds aloft includes the jet streams but they are different things. There are several factors that lead to the creation of Winds Aloft. The tilt and rotation of the earth divides the atmosphere into counter-rotating cells of air that encircle the globe at various latitudes. The rotation of the cells is driven by the movement of warm and cold air attempting to equalise pressure.
Other planets in our solar system also have cells like this and the number of cells is determined by properties of the planet.
On Earth there are 3 cells in each hemisphere: a Hadley cell at the equator flanked by a Ferrel cell and a Polar cell. The North and South hemispheres are mirrors of each other. As the Hadley cells at the equator shed warm air at altitude the Coriolis effect induces a curve in the motion of the wind in both the North and South hemispheres so that the sinking sub-tropical air is induced to move in an Eastward direction.
Due to the conservation of angular momentum the speed of the air mass increases as the length of the latitude decreases at ground level. The temperate jet streams have the potential for the strongest winds.
Cool air moving back to the to the tropics experiences a similar curve as it moves to the equator where the net result is a tropical wind moving Westward.
The jet streams are guided by the interplay of the Hadley and Ferrel cells at their edges.