Stop in for a cup of coffee

Took the dog out this morning and I hear this 'buzzing noise' Not deafening, but pretty loud. I'm like :wtf:. So I stop and focus on individual noises and its the combination of ice cracking and falling and mostly just all the dripping on this thin top sheet of ice. I think the snow is settling under it leaving a slight gap and it acts like an amplifier. Kinda like tapping on an empty can vs a full one.