For an explanatory essay describing a natural phenomenon, see details

Mirage. A mirage is an optical phenomenon produced by the continuous refraction and total reflection of light in air with an uneven refractive index under clear, windless or breezy conditions. Due to the uneven change of the refractive index of the air, the deformation of the object, and the disturbance of the breeze, the fairyland dissipated, which made it even more mysterious.

The air near the surface of the sea has a higher refractive index due to the lower sea temperature and moist water vapor, while the air above is warmer due to the sunshine temperature. In other words, the refractive index of the air layer above the sea surface decreases gradually with altitude from the bottom to the top. As light passes through this layer of air, it bends downward through continuous refraction.

The distant view of the sea is hidden below the horizon and cannot be seen directly. When the light rays of these scenes into the air continue to bend to the ground and reach the human eye, people will look against the light, and they will see that there is a strange scene above the sea that has never been seen before, like a fairy pavilion volley.

The moon is cloudy and sunny, this is one of a kind! I think according to the subject matter, don't blame me, I'm exercising you!

There are many natural phenomena; For example, the moon is cloudy, bright and round, and people have joys and sorrows.

Rain. Rain is a drop of water that falls from the clouds, the water on the surface of the land and the sea evaporates into water vapor, the water vapor on the rain ** appreciation (19 photos) rises to a certain height and then becomes a small droplet when cold, the ** collection of this rain (20 photos) Some small water droplets form a cloud, they collide with each other in the cloud, merge into large water droplets, when it is so big that the air can not hold it, it falls from the clouds, forming rain. Rain can occur in a variety of ways, from drizzle to continuous rain and downpour showers.

Rain is the most important source of fresh water in human life, and plants must also be nourished by rain and dew to thrive. But flooding caused by heavy rains can also bring great disasters to human beings.

When water on Earth is irradiated by sunlight, it becomes water vapor and evaporates into the air. When water vapor encounters cold air at high altitudes, it condenses into small water droplets. These small droplets are small, with a diameter of only millimeters and a maximum of millimeters.

They are small and light, held in the air by updrafts in the air. It was these small droplets of water that gathered together in the air to form clouds. For these small droplets to fall to the ground as raindrops, they would have to increase in size by more than 1 million times.

How do these small droplets grow their size to more than 1 million times? It mainly relies on two means, one of which is condensation and condensation increase. The second is to rely on the collision and growth of cloud droplets.

In the early stages of raindrop formation, cloud droplets mainly rely on the continuous absorption of water vapor around the cloud body to condense and condense themselves. If the water and gas energy sources in the cloud are constantly replenished and the surface of the cloud droplets is often supersaturated, then this condensation process will continue, causing the cloud droplets to grow and become raindrops. However, sometimes the amount of water vapor in the cloud is limited, and in the same cloud, the water vapor is often in short supply, so that it is impossible to make each cloud drop increase into a larger raindrop, and some smaller cloud droplets have to be merged into the larger cloud droplets.

If water droplets and ice crystals coexist in the cloud, the process of condensation and bloom increase will be greatly accelerated. When the droplets in the cloud increase to a certain extent, due to the increasing size and weight of the large droplets, they will not only catch up with the slower small droplets in the process of descending, but will also "swallow" more small droplets and make themselves stronger. When the large cloud droplets grow larger and larger, and finally the air can no longer support them, they fall straight from the clouds to the ground, becoming our common rain.

Rain scene (20 photos).

There are many types of rain, in addition to acid rain, colored rain, there are many interesting rains, such as frog rain, iron rain, gold rain, and even money rain. They are all masterpieces of tornadoes.

Red tide. Red tides are estuarine, oceanic, or freshwater algae that quickly accumulate in the waters, thus covering the entire sea or beach, turning the sea water blood red. This phenomenon is due to the accumulation of dense and visible clumps of phytoplankton on the surface of the water, and while some phytoplankton are not harmful, a small number of phytoplankton are highly toxic and can cause the death of fish, birds and marine mammals.

In some cases, even humans have been harmed by the red tide, although no deaths have been recorded in the red tide.

How big the snowflakes are.

The poet Li Bai has a famous poem when describing the snowflakes of Yanshan: "The snowflakes of Yanshan are as big as a seat." "Are snowflakes really that big? Actually, snowflakes are very small. Don't say that there is no record in the history of snowflake science that is "as big as a seat".

Record, even "goose feather heavy snow", is not easy to encounter.

In fact, the individual snowflakes we can see are generally between millimeters in diameter. Such tiny snowflakes can only weigh on a very precise analytical balance, about 3,000 to 10,000 snowflakes combined to weigh one gram. A scientist roughly counted that there are 6,08 billion snowflakes in one cubic metre of snow, more than the total population of the planet.

The size of the snowflake crystals depends entirely on the temperature at which the water vapor sublimates and crystallizes. The snow crystals formed in the very cold are so small that they are barely visible, and only when they shimmer in the sunlight can one detect their presence as diamond powder.

According to research, temperature has an effect on the size of snow crystals: when the air temperature is -36, the average area of snow crystals is millimeters squared; When the air temperature is -24, the average area is millimeters squared; When the temperature is -18, the average area is millimeters squared; -6, the average area is millimeters squared; At temperatures of -3, the average area of snow increases to millimeters square.

People have a misconception that some literary works like to describe the cold weather as "goose feathers and heavy snow". In fact, the "goose feather snow" is a product of the temperature close to about 0, and it is not a symbol of a cold climate. Conversely, the larger the snowflakes, the higher the temperature at that time.

Heavy snow rarely occurs in the severe cold of Sanjiu, and it is only in late autumn and early winter or late winter and early spring that it is possible to have heavy snow with goose feathers. The so-called goose feather snow is not actually a single snowflake, but is formed by many snowflakes sticking together. A single snowflake crystal will not exceed 10 mm in diameter, and at most it will be the size of our fingernails, which cannot be called goose feather snow.

In the case of relatively high temperatures, snowflake crystals are easily linked to each other, a phenomenon called snowflake merging. Especially when the temperature.

When the air is close to 0, the combination capacity of snowflakes is particularly large, and hundreds of snowflakes live together and form a goose feather snow. Cause.

Strictly speaking, goose feather snow cannot be called snowflakes, it is just an aggregate of many snowflakes.

[1] The full moon is missing.

I don't know if the moon is full or absent. In my eyes,

Snow watching in winter. Qingfeng Elementary School Class 5 (5) Jiang Haozuo.

Suddenly, like a night of spring breeze, thousands of trees and pear blossoms bloom. "In the cold and bleak winter, what we children look forward to most is snow. Nature paints a world of pink and jade with the brush of snow, bringing us infinite excitement and surprise.

Before the snow, the sky was a leaden color. I don't know from what moment it started, and the snowflakes fell silently. At first, the snow was not too big, nor too dense, scattered like catkins fluttering, and like the white swans gently fluttering their wings, and small feathers fluttering and falling.

At this point, I would rush outside the house, raise my face to greet them, and reach out to pick up these lovely elves. Ah, my dark red down jacket is covered with snowflakes, and it looks so eye-catching! I watched them with wide eyes and fascination.

See, each snowflake is hexagonal, and that corner has a star-branched, needle-shaped, columnar-shaped ......It's a lot of variety! Gradually, the snow became heavy and dense, just like who shook the jade tree qionghua in the sky, the petals flew down one after another, you hugged me, I hugged you tightly, weaving a huge white net between heaven and earth, and everything was covered by this gentle snowflake. At this moment, everything is so beautiful and so silent.

I folded into the house and looked out the window at the snowflakes as if I had become one of them, and I heard the laughter of the snowflakes, really, their joy, I could feel it.

But sometimes the snow that falls from the sky does not seem to be hexagonal petals, but small snow particles, like white sugar, and like small silver beads, who can tell me why? They fall straight and fast, as if heading for a goal. If you catch the howling wind, the snow will weave densely and even horizontally, open your mouth and taste it, hey, say it is like sugar but not sweet, like monosodium glutamate but not fresh, like salt but not salty.

They just hung up the white snow curtains, the carpets were laid on the ground, the buildings were dressed in white robes, the trees were full of "pear blossoms", and everything was full of poetry and picturesqueness. My friends and I came out, we built snowmen, had snowball fights, and carved dense footprints on the soft snow......

By the time the snow melted, it was surprisingly cold. Under the winter sun, the snow turned into tears that could not bear to leave. How nostalgic they are for this world!

Maybe the snow in the shade will last a few more days, but the original soft body has become transparent and hard, and they are destined to say goodbye to us. They have fulfilled their mission to spread joy and holiness to the earth.