Angles of Elevation and Depression are used in measuring heights and distances in trigonometric applications using right triangles. These angles are made when we look up or down to view objects. Devices are available to measure angles of elevation and depression. These measured angles can be used in measuring heights and distance which are either tedious or impractical to measure, by modelling the situation into right triangles.
Angle of Elevation and Depression
In the above picture a man standing on a cliff is simultaneously viewing an airplane flying in the sky and a boat sailing in the lake beneath. The angles of elevation and depression are marked as xº and yº respectively.

Angle of elevation is the angle formed by the line of sight of an observer with the horizontal while he is viewing an object upward.

Angle of Elevation

The angle of elevation is a degree measure indicating the gradient of the line of sight. As this angle can be measured using devices, this measure can be used to determine large heights and long distances, which are impractical to physically measure.

Elevation of Sun is a degree measure similar to angle of elevation, which represents the the distance of the center of Sun's disk from the Horizon. Elevation of Sun is also used frequently in Right triangle model applications.

Angle of Elevation Example

In the above diagram Sun's elevation is marked as the angle between the line joining the Sun and the tip of the shadow and the horizontal.