What happens when the elevator is deflected upwards?

When the elevator is deflected upwards, it changes the angle of attack of the tail of the aircraft. This action increases lift on the tail, which has the effect of decreasing the downward force produced by the tail. As a result, the aircraft's nose will pitch up, causing the aircraft to climb. This is due to the aerodynamic principles governing how control surfaces alter airflow and lift over the wings and tail surfaces. When pilots want to ascend in altitude, they pull back on the control yoke or stick, thereby elevating the elevator and enabling the aircraft to climb.