Civil Sunset vs. True Sunset
Posted: Wed Jan 03, 2007 7:21 pm
Hi Y'all -
I have a bit of an odd question here. I use HB to turn on and off my exterior lights at sunrise and sunset, but I don't turn them on just at sunrise and sunset, but sometime before (or after depending) these events actually occur. Now, I'm wondering what HB defines as sunrise and sunset. I did a bit of research - there are various types of these sunrise and sunset events. There is the actual sunrise/sunset, there is the civil sunrise/sunset, nautical sunrise/sunset, and finally astronomical sunrise/sunset.
The one I'm interested in is the civil sunrise/sunset. As I understand it, that's the point when the sun appears just enough to see outside but not quite dark (the transition point). In the summer time, I have the exterior lights come on some time after the actual sunset when it's dark enough to need the lights on. Otherwise I'm the only idiot on the block with the lights on when everything is still bright outside.
On the other hand, in wintertime, the days are short and it appears that I have to turn on the lights before the actual sunset so in a sense the time of civil twilight in the winter and summer are not the same time apart. For example, in the summer time the civil sunset is like an hour after the sunset. And in the winter time, the civil sunset is something like 15 minutes after the sunset. So I can't use a constant value year round, is there some formula I can use to determine at what point after/before sunrise/sunset to actually turn on the lights?
Or I could use an X10 dusk/dawn sensor. But I've had a hard time placing one of those - I find that the lights in the room confuse my dusk/dawn sensor and had to keep the shades drawn all the time to keep the outside light focused on the sensor module.
Anyway, as a geek, that's the easy way out! I wanna do this some other way with a script in HB to compute the civil sunrise/sunset times.
I have a bit of an odd question here. I use HB to turn on and off my exterior lights at sunrise and sunset, but I don't turn them on just at sunrise and sunset, but sometime before (or after depending) these events actually occur. Now, I'm wondering what HB defines as sunrise and sunset. I did a bit of research - there are various types of these sunrise and sunset events. There is the actual sunrise/sunset, there is the civil sunrise/sunset, nautical sunrise/sunset, and finally astronomical sunrise/sunset.
The one I'm interested in is the civil sunrise/sunset. As I understand it, that's the point when the sun appears just enough to see outside but not quite dark (the transition point). In the summer time, I have the exterior lights come on some time after the actual sunset when it's dark enough to need the lights on. Otherwise I'm the only idiot on the block with the lights on when everything is still bright outside.
On the other hand, in wintertime, the days are short and it appears that I have to turn on the lights before the actual sunset so in a sense the time of civil twilight in the winter and summer are not the same time apart. For example, in the summer time the civil sunset is like an hour after the sunset. And in the winter time, the civil sunset is something like 15 minutes after the sunset. So I can't use a constant value year round, is there some formula I can use to determine at what point after/before sunrise/sunset to actually turn on the lights?
Or I could use an X10 dusk/dawn sensor. But I've had a hard time placing one of those - I find that the lights in the room confuse my dusk/dawn sensor and had to keep the shades drawn all the time to keep the outside light focused on the sensor module.
Anyway, as a geek, that's the easy way out! I wanna do this some other way with a script in HB to compute the civil sunrise/sunset times.
