6.18 Twilight

6.18.2 Define:

(a) sunrise;

• Sunrise occurs when the first visible part of the sun passes above the horizon.

(b) sunset;

• Sunset occurs when the last visible part of the sun passes below the horizon.

(c) daylight;

• The period from the start of morning civil twilight until the end of evening civil twilight.

(d) twilight;

• The light from the sun you see before sunrise (morning twilight), and the light you see after sunset (evening twilight).

(e) morning civil twilight (MCT);

• The period from when the centre of the sun is 6° below the celestial horizon,
• up until sunrise.

(f) evening civil twilight (ECT).

• The period from sunset
• up until when the centre of the sun is 6° below the celestial horizon.

6.18.4 Describe the factors that affect the times of sunrise and sunset (daylight). 

6.18.6 Describe the factors that affect the duration of twilight. 

6.18.8 Describe the factors that affect daylight conditions. 

6.18.10 Derive or calculate the MCT and ECT at a given location (UTC, NZST and NZDT)

DAYLIGHT TABLES

Daylight Zones and Tables