Define the term "wind shear."

Wind shear refers to a significant change in wind speed and/or direction with height in the atmosphere. This phenomenon is particularly important in meteorology and aviation because it can greatly affect aircraft performance, particularly during takeoff and landing.

When wind shear occurs, it can lead to turbulence and can cause dramatic changes in lift, presenting challenges for pilots. For example, if a pilot is taking off and suddenly encounters an increase or decrease in headwind or tailwind due to wind shear, it can affect the aircraft's speed and control.

Other options do not accurately describe wind shear: a sudden increase in temperature pertains to thermodynamic changes in the atmosphere, the amount of rainfall is related to precipitation measurements, and the force of wind at ground level refers to surface wind conditions. None of these capture the essence of how wind changes with altitude, which is central to the concept of wind shear.