Spectral analysis of sunrise time variation

Circlotron · 5th May 2007, 02:44 PM

A couple of days ago I was having a lazy afternoon and I fell asleep on the couch (sofa) and proceeded to dribble on the pillow.

I had a dream and in it I was thinking about how sunrise time varies with the seasons, and whether or not it follows a sinusoidal pattern, and if it doesn't then is there some kind of hidden information in the harmonics?

Tonight I got the sunrise times of Perth, Western Australia, graphed them in a spreadsheet and also imported the data into Cool Edit as an ascii text file to do the harmonic analysis (and listen to the waveform - nothing exciting btw).

This is the spreadsheet graph showing actual time of day:

Circlotron · 5th May 2007, 02:46 PM

Cool Edit waveform:

Circlotron · 5th May 2007, 02:47 PM

Spectral analysis:

I_Forgot · 5th May 2007, 05:27 PM

Last time I looked, sine waves didn't have any harmonics.

So much for THAT idea...

I_F

Christer · 5th May 2007, 06:07 PM

The main reason for seasons is the angle of the earths rotational axis. However, AFAIk this angles is not perfectly fixed but has a sligth variation (or wobble). Further, earths orbit is elliptical, not circular, even though it is very close to a circle. Without checking the maths, I would presume both of these effects could contribute to the harmonics.

Aengus · 5th May 2007, 06:17 PM

White.

Circlotron · 6th May 2007, 04:28 AM

Quote:

Originally posted by I_Forgot
Last time I looked, sine waves didn't have any harmonics.

So much for THAT idea...

I_F

How would you define "first harmonic" then?

Tom2 · 6th May 2007, 08:09 AM

I think the waveform is related to the analemma.

Tom

I_Forgot · 6th May 2007, 05:48 PM

Quote:

Originally posted by Circlotron

How would you define "first harmonic" then?

There is no such thing as a "first harmonic". Harmonics start at the 2nd. I believe you are thinking of the "fundamental".

I_F

Pjotr · 6th May 2007, 05:58 PM

Me think you have harmonics: 1st, 2nd, and so on

OR

You have overtones: Fundamental, 1st overtone, 2nd overtone, and so on

But not mixed up.

Cheers

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5th May 2007, 05:27 PM	#4
I_Forgot diyAudio Member Join Date: Jan 2005 Location: Phoenix, Az.	Last time I looked, sine waves didn't have any harmonics. So much for THAT idea... I_F

5th May 2007, 06:07 PM	#5
Christer diyAudio Member Join Date: Sep 2002 Location: Sweden	The main reason for seasons is the angle of the earths rotational axis. However, AFAIk this angles is not perfectly fixed but has a sligth variation (or wobble). Further, earths orbit is elliptical, not circular, even though it is very close to a circle. Without checking the maths, I would presume both of these effects could contribute to the harmonics.

5th May 2007, 06:17 PM	#6
Aengus diyAudio Member Join Date: Apr 2004 Location: Victoria, BC	White.

6th May 2007, 08:09 AM	#8
Tom2 diyAudio Member Join Date: Jun 2004 Location: Central CA	I think the waveform is related to the analemma. Tom

6th May 2007, 05:58 PM	#10
Pjotr diyAudio Member Join Date: Nov 2002 Location: Netherlands	Me think you have harmonics: 1st, 2nd, and so on OR You have overtones: Fundamental, 1st overtone, 2nd overtone, and so on But not mixed up. Cheers

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