What does "sleep" mean in summer?

Entering crouching means entering the dog days, which means that the hottest summer and high temperature season of the year have begun.

"Three volts" refers to the first, middle and last three volts, which is about mid-July to mid-August. After the summer solstice, although the days are getting shorter and the nights are getting longer, the days are longer than the nights in a day. Every day, the ground absorbs more heat than it emits, and the temperature near the ground is getting higher every day.

During the "three volts" period, the ground absorbs almost more heat than it emits, and the weather is the hottest. After that, the heat absorbed by the ground began to be less than the heat emitted by the ground, and the temperature gradually decreased. Therefore, the hottest time of the year generally appears in the "three volts" summer solstice.