In navigation and geography, from which reference direction does an azimuth angle conventionally originate when measured on a horizontal plane?

Introduction / Context:
Azimuth is a term used in navigation, surveying, astronomy and geography to describe the direction of an object from an observer. It is usually measured as an angle in the horizontal plane. To interpret or compute an azimuth correctly, you must know the reference direction from which the angle starts. This question asks for that conventional starting direction on a standard compass-bearing system.

Given Data / Assumptions:
- We are dealing with conventional azimuth as used in navigation and maps.
- The options are the four cardinal directions: south, north, east and west.
- Azimuth is measured horizontally around the observer in degrees from a reference direction.

Concept / Approach:
In the most common convention, azimuth angles are measured clockwise from geographic north. Thus an azimuth of 0 degrees corresponds to north, 90 degrees to east, 180 degrees to south and 270 degrees to west. Some specialised fields may use different conventions, but general navigation and geography use north as the reference. Therefore, the correct answer is north.

Step-by-Step Solution:
Step 1: Recall the standard definition of azimuth in navigation: angle measured clockwise from north along the horizon. Step 2: Note that at 0 degrees azimuth, the direction is north. Step 3: At 90 degrees, the direction is east; at 180 degrees, south; and at 270 degrees, west. Step 4: Since the question asks from which point the azimuth originates, the answer is the direction corresponding to 0 degrees, namely north.

Verification / Alternative check:
If you look at typical compass roses printed on maps, you will usually see azimuth markings increasing clockwise starting at north at the top. Surveying instruments and GPS devices also report azimuths measured from north in this standard way. This consistent practice across navigation and mapping confirms that north is the conventional origin for azimuth measurements.

Why Other Options Are Wrong:
South: South corresponds to 180 degrees azimuth, not the starting point.
East: East corresponds to 90 degrees azimuth, a quarter-turn from the starting direction.
West: West corresponds to 270 degrees azimuth, three quarters of a full turn from the starting direction.

Common Pitfalls:
Students sometimes confuse azimuth with bearing systems that may be described relative to different quadrants, leading them to think that east or south might be the starting direction. Another mistake is mixing up azimuth with altitude in astronomy, where altitude is measured up from the horizon. Remember that azimuth is a horizontal angle, and in standard navigation it always starts from north and increases clockwise.

Final Answer:
An azimuth angle conventionally originates from north as the reference direction.