Earning vs power consumption

Is there any particular reason why most days my power cost is 30% of earnings, but then all of a sudden yesterday there was a spike in earnings so that electricity only accounted for 5% of earnings that day?

Is it because of the type of coin it was mining or fewer people mining since its Xmas? Just curious as I've been mining for a week and only had this spike yesterday.

Many thanks.

Welcome to crypto currency.

HAPPY HASHING!

If you are mining Scrypt, its probably because a miner in the pool found a block with over $100,000 in transaction fees. So everyone who was mining Scrypt yesterday earned more than usual.