text: there is no unbalance of pitching, yawing, or 
  rolling moment. 
  the airplane traverses a 
  sharp wind shear equivalent to a horizontal 
  gust, the resulting change in airspeed will 
  disturb such an equilibrium. For example, if 
  the airplane encounrers a sharp horizontal 
  gust which reduces the airspeed 20percent,the 
  new airspeed (80 percent of the original value) 
  produces lift and drag at the same angle of 
  attack which are 64 percent of the original 
  value. The change in these aerodynamic forces 
  would cause the airplane to accelerate in the 
  direction of 
  force. 
  That is, the airplane would accelerate down 
  is 
  forward until a new equilibrium 
  and 
  achieved. 
  there would be a 
  change in pitching moment which would 
  produce a response of the airplane in pitch. 
  The response of the airplane to a horizontal 
  gust will differ according to the gust gradient 
  and airplane characccristics. Gmcrally, 
  if the 
  airplane encounters a sharp wind shear which 
  reduces the airspeed, the airplane tends to sink 
  and incur a loss of altitude ‘before equilibrium 
  conditions are achieved. Similarly, 
  the 
  airplane encounters a sharp wind shear which 
  increases the airspeed, the airplane tends to 
  float and incur a gain of altitude before equilib- 
  rium conditions are achieved. 