It turns out that there is such a big difference between snow accumulation and snowfall? | Expo Daily

It turns out there is such a big difference between snow accumulation and snowfall?

Since December 10, large-scale snowfall has occurred in North China, Huanghuai and other places. The impact of rain, snow and cold waves on transportation, urban operations and other aspects has attracted attention. However, there is a little knowledge that snow accumulation and snowfall are two different concepts. Snow accumulation refers to snow covering an area that reaches more than half of the visible area of ​​the area. Snowfall refers to when the temperature in the clouds is too low, small water droplets form ice crystals, and they are still snowflakes when they fall to the ground. Snow accumulation is one of the important sources of water resources in China. In northern China, especially in the arid and semi-arid areas of the northwest, snow accumulates for a long time in winter and the amount of snow is abundant. All walks of life, especially agricultural and animal husbandry production, are closely related to seasonal snow accumulation.

Winter snow plays a vital role in agricultural production. Soil moisture and spring irrigation are highly dependent on snowmelt. On the other hand, snow is also an important and sensitive factor in climate change. Therefore, snow monitoring has always been one of the important research areas that is widely valued at home and abroad.

Not only do snowfall and snow accumulation have different meanings, the snow we often see is also divided into dry snow and wet snow. Dry snow is generally distributed in Northeast China, Xinjiang and other places. There is only ice and air in the snow without water. This kind of snow is dry snow; while wet snow is mostly produced in the south, which refers to snow with a water content of more than 5%.

Source: pixabay

If you don't sleep when you should , your nerve cells will automatically fall asleep

Some scientists once conducted an experiment in which they removed the brains of mouse embryos at 16-18 days of development, extracted the nerve cells therein, and cultured them in vitro. At the same time, they used an electrode array to monitor the electrical activity of each nerve cell and found that these nerve cells each emitted electrical pulses and had no connection with each other.

However, as time went on, the electrical activity of the nerve cells gradually became synchronized, and by the 10th day of culture it was completely synchronized. Even nerve cells that were far apart sent out electrical pulses at the same pace, and the overall electrical activity showed slow waves similar to those of animals during NREM sleep, indicating that these nerve cells will automatically enter a sleep state in the absence of external stimulation.

There may be several reasons why nerve cells fall asleep. First, the resources consumed when awake cannot always be fully supplied, so sleep is needed to replenish them, just like when the ammunition is used up in a war, you have to replenish the ammunition before you can fight again. Second, the waste generated when awake cannot be cleared away in time, so sleep is the time to clear the waste. Third, working when awake will cause damage and changes to the nerve cells themselves. If they are not regulated and repaired through sleep, they cannot continue to work.

Ginkgo: I have been lonely for 270 million years!

Ginkgo is not only tenacious, but also a well-known "living fossil": it has existed on Earth for hundreds of millions of years.

Speaking of the oldest large plant on earth, it is probably the ginkgo. Modern ginkgo has no living relatives. There is only one class under the Ginkgo family - Ginkgoales; under this class, there is only one order - Ginkgoales; under the Ginkgoales, there is only one family, one genus, and one species - Ginkgo because all its relatives have disappeared from the earth's stage in countless catastrophes over the past 270 million years.

Ginkgo's own habitat was also shrinking, and the tree became extinct in North America about 5 million years ago and in Europe about 2.6 million years ago.

Since 2.6 million years ago, the Earth has experienced several ice ages, and the habitat of ginkgo has been gradually compressed. Although ginkgo has escaped various extinction events and survived several ice ages due to its flexible genes, time is running out for ginkgo.

Of course, ginkgo trees still demonstrated their tenacious vitality and even set another world record: in the atomic bomb explosion in Hiroshima in 1945, most of the creatures within a few kilometers of the explosion center were destroyed, but 6 ginkgo trees miraculously survived and are still thriving.

Source: pixabay