Red Sky at Night
Explanation
This is the old adage:
Red sky at night, sailor's delight. Red sky in the morning, sailor takes warning.
- In temperate zones, weather systems move from west to east.
- Clouds to your west are coming towards you, clouds to your east are moving away.
- Red light Passes through air more easily than blue
- When the sun is in the west, the light from it travels through hundreds of kilometers of air towards where you are. The clouds near are you act as the screen where the red light is projected. If the clouds look red, it is because the light from the sun got all the way there. The light was not blocked by any clouds, further to your west. This indicates there few clouds to your west.
- When the sun is in the east, the light is coming from east to west. A red sky in the morning indicates the clear zone is moving away from you. The clouds overhead are moving in. There may be cloudy weather ahead.
Conclusion
The red sky at night tells you there are no clouds moving towards you. A sign of clear weather coming.
The red sky in the morning tells you the clear weather is moving away. Clouds are moving in.