What is the meaning of "Tears on the Moon" in Zhang Ji's poem a night-mooring near maple bridge?

When the moon sets, crows crow ":It's almost dawn, and crows have begun to sing.

This is the first sentence of night parking near Fengqiao.

The whole poem is:

Crows fell on the moon, crowed coldly, slept on maple trees, and slept in fishing lanes by the river.

In the lonely Hanshan Temple outside Suzhou, the bell that rang in the middle of the night reached the passenger ship.

Frost jathyapple falls: here refers to the dawn; Five bodies: here refers to the crow's cry; Frost all over the sky: The poet Zhang Ji mistook ice fog for frost. Meteorology, fog refers to a large number of water droplets or ice crystals suspended in the air near the ground, making the horizontal visibility less than1km; Frost is a white ice crystal formed by direct condensation of water vapor in the air on the ground or ground objects. Obviously, fog refers to the condensation of water vapor in the air, which can be water droplets or ice crystals; Frost only refers to the surface solid condensation of water vapor. When the poet stayed in Qiao Feng at night, it was cold and foggy. The fishing fire reflected by ice crystals and the light of moonlight (or the afterglow of the moon) enter the poet's eyes, and he thinks it is the light reflected by frost. During the Tang Dynasty 1000 years, people's understanding of many natural phenomena was superficial. They either refer to the ice fog in the air and the frost on the ground as frost, or think that the frost on the ground is formed by "frost" landing in the air. The first frost is one of the 24 solar terms, hence the name. Therefore, it is logical for Zhang Ji to use "frost all over the sky".

Ice fog, also known as ice fog, is more common in winter, but modern people often mistake it for snow because it looks like "snowflakes" falling one after another. In fact, there is a difference between snowflakes and ice fog. Morphology, snowflakes are usually a number of ice crystals stuck together, bigger and thicker, and look furry; Ice fog is countless single ice crystals, smaller and thinner, with smooth crystal faces. In Genesis, snowflakes were condensed from clouds and appeared on cloudy days. Ice fog is formed on sunny days and can reflect sunlight and moonlight.

Although this poem is about specific scenery, it actually expresses the author's loneliness and faint sadness.

It's almost dawn, and the crows have begun to sing. Seeing the ice fog all over the sky makes people feel even colder.