This is not rocket science chaps - the clue is in the terms "airspeed" (the speed at which you are moving through the air and measured by your Air Speed Indicator) and "groundspeed" (the speed at which you are moving across the ground and measured by doppler/GPS/INS etc).
On a nil-wind day your groundspeed will equal your airspeed whichever direction you fly in (assuming at lowish levels where TAS/IAS differences do not apply).
On a day when the wind is 20 kts from the North, when you are heading North at 60 kts Airspeed you will have 40 Kts groundspeed; when you are heading South at 60 kts airspeed you will have 80 kts groundspeed. In both situations, the power and attitude will be the same as the IAS is the same!
When you are heading East or West with the same 60 kts airspeed and the same 20 kts wind from the North, you will have 60 kts groundspeed.
If you turn from North to South using the same 60 kt attitude and a constant angle of bank, the airspeed will not change but your groundspeed will gradually increase.
Turns at low level are frequently carried out using external visual references because you are close to them and it is unnatural to fly on instruments close to the ground. It is a human failing, not a physics related one, that in such a turn from into-wind to down-wind, a pilot wants to keep his apparent speed (the groundspeed which he is judging visually) the same and so he does not maintain the correct attitude but subconciously adjusts it. He therefore loses airspeed as he turns downwind but only because he has changed the attitude to change the airspeed.
In turbulence or wind-shear, the strength and direction of the wind changes suddenly and the same effects are seen: If you are flying North at 60 kts IAS with a 20 kt wind from the North you will have a groundspeed of 40 kts - if, in an instant, the wind changes to 20 kts from the South you will suddenly have 40 kts IAS and 40 kts GS until the aircraft accelerates due to it's selected 60 kt attitude up to the point where you are at 60 kts IAS with 80 kts GS.
The reason that wind-shear and turbulence are so dangerous, especially at low level, is that the wind can alter constantly in both strength and direction so the pilots IAS is constantly changing and therefore the power required to maintain height is constantly changing. If you are at a low enough IAS (on approach for example) then the IAS fluctuations can cause you to lose ETL (which leads to increased power requirements and heading changes) and even leave you with negative IAS and positive GS.
The solutions are:
a. Never fly in turbulence or windshear (not very pratical)
b. Try to visualise the flow of air through/around the features you are flying over (at least the you can anticipate the turbulence)
and c. Constantly cross refer to instruments (this may save your life)