What two conditions are known to normally cause an increase in lift?

The reasoning behind the choice of increased angle of attack and increased speed as the conditions that normally increase lift is grounded in the principles of aerodynamics.

When an aircraft's angle of attack is increased, more airflow is directed over the wings, which enhances the pressure difference between the upper and lower surfaces of the wings. This phenomenon increases lift, up to a point known as the critical angle of attack, beyond which lift can decrease due to stall.

Simultaneously, an increase in speed also enhances lift. As speed increases, the flow of air over the wings becomes more dynamic, leading to a greater volume of air being displaced and thus creating more lift. This relationship is captured in the lift equation, which shows lift is proportional to the square of the velocity of the aircraft.

Together, these two factors influence the ability of an aircraft to generate lift effectively and are fundamental concepts in understanding flight mechanics.