World Meteorological Day

Spring shortens by 30 seconds every year?

Rainbow is a semi-arc?

A cumulonimbus cloud is equivalent to 100 the weight of an elephant?

Can you really feel cold when you are empty and lonely?

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March 23

World Meteorological Day

These cold knowledge about meteorology

How much do you know?

Let's get to know each other!

Spring shortens by 30 seconds every year?

The spring mentioned here is not the spring in meteorology, but the time from vernal equinox to summer solstice in astronomy. For thousands of years, this period in the northern hemisphere has been shortened by 30 seconds every year.

Why did this change happen? First of all, the earth's orbit around the sun is not a complete circle, but an ellipse. This means that the distance between the earth and the sun will not be the same forever. Perihelion is at the beginning of 1 month every year, and apohelion is at the beginning of July every year. Although this distance is insignificant compared with the total distance between the earth and the sun, it is difficult for people to notice it at ordinary times, but this difference will affect the speed of the earth in orbit. Near perihelion, the earth moves faster, while at apohelion, the situation is just the opposite. Winter in the northern hemisphere coincides with the earth approaching perihelion, and the revolution speed is relatively fast, so winter passes quickly. In summer, the earth is far from the sun, and the revolution speed is slow, so the summer passes slowly.

1246, the earth reached perihelion on the winter solstice (65438+2 1 February), and in 2020, the earth reached perihelion on 65438+1October 5. About 3000 AD, the earth will not reach perihelion until 65438+1October 20th. So spring and summer are getting shorter and shorter, and summer and autumn are getting longer and longer, which is natural.

Rainbow is a semi-arc?

In fact, if there is no ground restriction, the rainbow should be a complete circle, and the rainbow we see is semi-arc because it is blocked by the horizon.

Because of the different refractive index, each color of light wave has a specific bending angle. The refraction angle of red light in sunlight is about 42 degrees, and that of blue-purple light is 40 degrees. So, if you draw an imaginary line connecting the back of your head with the sun and extend it in front of you, the place that forms an angle of 40-42 degrees with this line is usually where the rainbow is. Now there are countless parallel rays entering and exiting water droplets, and what you can finally see is a collection of beams that are about 42 degrees from the parallel incident rays, so you get a cone with the eyes as the vertex, and the arc at the bottom of this cone is a rainbow.

A cumulonimbus cloud is equivalent to 100 the weight of an elephant?

Cloud is a visible polymer with ungrounded bottom, which is composed of water droplets, supercooled water droplets, ice crystals or their mixture formed by condensation or sublimation of water vapor in the atmosphere.

Clouds that look as light and soft as cotton actually have a lot of weight. Research data show that, on average, the weight of a cumulonimbus cloud can reach 500 tons, which is equivalent to the weight of 100 elephant.

Can you really feel cold when you are empty and lonely?

Emptiness, loneliness and cold are often manifested as a psychological state, but they are actually a physiological state. Experiments show that when human beings are rejected or feel lonely, the average temperature of fingers will drop by 0.37.

This is because when people feel external pressure, the nervous system (mainly autonomic nerves) will respond, which will lead to more blood flowing to core organs such as the heart and brain. Although this mechanism can lower the body temperature, the body surface temperature will also decrease due to the contraction of blood vessels.

So, when you are lonely, you might as well have a cup of hot drink to warm yourself up.

Will sleep quality be better in rainy days?

Many people like to sleep in rainy days. The rustling sound outside is accompanied by a hint of coolness. Gray weather makes the surroundings darker and makes them sleep better.

In fact, this is mainly because rain is white noise, which means that the power spectral density is constant in the whole frequency domain. The sound of waves beating against rocks and the sound of wind blowing through leaves are all white noise, which can be said to be a "harmonious" therapeutic sound. The spectrum of white noise contains all frequency components, and it is evenly distributed, shielding other spectrum components, that is, the sound of rain shields external interference, so some people will feel that the sleep quality is better when it rains.

Why is the weather forecast in your eyes inaccurate?

Perhaps in our daily life, we can always hear some people say that "the weather forecast is unreliable". So is the weather forecast really "unreliable"?

In fact, although the weather forecast cannot guarantee the accuracy of 100%, it is reliable most of the time. On July 5, 2020, China Meteorological Bureau held a special news conference on the flood season in 2020. Wang Jianjie, director of the Central Meteorological Observatory, said that meteorological forecasting and early warning provided meteorological support and support for China's disaster prevention and mitigation and the public's right to know, and the accuracy of weather forecasting in China reached 88%.

So why can't the weather forecast be 100% accurate? This is because meteorological science belongs to forecasting science and has certain uncertainty. In addition, not every region has detailed monitoring stations, and the weather forecast is probabilistic. For example, in summer, strong convective weather occurs frequently, and due to terrain and other factors, there is more local precipitation, and the possibility of forecasting errors will increase. Based on the current level of science and technology, the accuracy of weather forecast can not reach 100%, but the meteorological department will try its best to improve the accuracy of forecast.

Does the climate have anything to do with people's looks?

People's appearance is closely related to the climate. People living near the equator have short necks, obviously small heads and wide noses in order to resist the hot weather. This structure is conducive to their internal heat dissipation. In cold areas at high latitudes, in order to resist the severe cold, people often raise their noses and long nasal passages to buffer the inhaled cold air. As far as head shape is concerned, residents in cold regions and temperate regions have large heads, round heads and relatively flat faces, which are very conducive to heat preservation and reduce heat dissipation.

People's tastes change with temperature?

People's tastes will change subtly with the change of temperature. The lower the temperature, the easier it is for taste buds to feel salty. Sour taste is the opposite, and the higher the temperature, the easier it is to be perceived. When the temperature reaches above 37℃, we can feel the bitterness most strongly. The sweetness is not easy to detect except at 35, and can be well detected at other temperatures.

The article is synthesized from China Meteorological Bureau, China Meteorological Science Popularization, Science Popularization China, Sichuan Association for Science and Technology, etc.