Curious spell effects

Didn’t know exactly how to categorize this. I did it as Norse Magick because I used the language and runes.

Anyway here’s what happened:
I was doing this spell to strengthen a friendship between me and another person. The sigils are made from our names and the runes spell out Bera Binda which is old Norse for binding of the heart. I opened the sigils first and then energized the drawing while intoning those Norse words. After some time I paused for a bit and I noticed a strange freezing air emanating from the drawing and it actual got cold enough to make me shiver.

Could this be an effect of the Binda aspect reducing the vibration of atoms? Or something else entirely?