Everything in St. Petersburg is anomalous warm winter(oh, I wish I could jinx it!), and I, quite tired from the two previous winter reconstructions of the events of the film “The Day After Tomorrow,” am incredibly happy about this. Moreover, a year ago, around this time, there was already a frost outside the window of -20°. Snowboarders and skiers will have artificial snow on the slopes, so they won’t be offended, but I can live well without it.

But while the weather is shaking around zero, every morning turns into a dilemma for me: what to wear so as not to freeze and not get sweaty. And this is where two excellent sites with very accurate weather forecasts come to my aid. At one time, my friend helped me find them, but he doesn’t write on LiveJournal, so I’ll bring the light to the people. Those who know about them, do not rush to throw eggs at the button accordion, because many still go to the stupid and lying Gismeteo and Yandex to find out the weather.

At the bottom short review two excellent sites: RP5 And YR.no, as well as answers to several questions that may arise after getting to know them. If it seems like there are too many letters, just take into account my recommendations and believe that these two resources have never failed or deceived.

This site, a guest from Norway, unlike RP5, in addition to being very accurate forecasts has very beautiful design. There is no Russian language, however. But there is English (switches in the upper right corner).
Feature of the site - a bunch different ways providing information, ranging from simple forecast tables familiar from Yandex for 9 days in advance (it is worth noting that the decoding is still very detailed), and ending with graphs and weather maps that change over time.
Personally, for me, the optimal and most understandable graph seems to be a moderately “loaded” graph, which can also acquire a line for pressure and a cloud diagram if you click on the Detailed button on the left, but this information seems unnecessary to me. The blue bars on the time axis are again the precipitation level in millimeters.

Now I will answer a couple of questions that may arise after reading these sites:

Q: Where do the British and Norwegians get their information about our weather? Our hydrometeorological center certainly knows better!
A: Not at all. Both the Hydrometeorological Center and everyone else know exactly the same thing about the actual weather. All information is collected by ground-based weather stations and made publicly available in the system of free international exchange of weather data. Now anyone who has a supercomputer with a thousand or two processors can take this data, process it and try to predict what the weather will be like in a particular place in the near future. It's just a matter of who can do it more accurately.

Q: It is not clear to me when precipitation is designated as 2 mm/6 hours. What to really expect?
A: Very easy to understand. Here's how RP5 explains it:
"The ratio is direct: 1 mm corresponds to 1 liter per 1 square meter. That is, 12 mm is a large 12-liter bucket; 10 mm - 10 liter bucket; 0.5 mm - half-liter bottle; 0.2 mm - a glass of water per 1 square. meter. Perhaps this explanation is not very solid, but it is understandable."
This opens up new horizons compared to those weather forecasts where rain, regardless of the predicted intensity, is indicated by a droplet or an umbrella. You can understand whether this umbrella is needed at all by these millimeters: 0.2-1 mm is very little, and most likely means heavy rain in places (that is, all 10 millimeters will fall on 10% of the city, and the sun will shine over the remaining 90%) . And 4-10 mm is already an impressive amount, spread over a huge area, and most likely the rain will continue to fall for a long time and everywhere.

Q: What rain, it’s winter here, frost -30! How to measure snow in millimeters?
A: Simply multiply by 10. 1 millimeter of precipitation equals 1 centimeter snowdrift.

Q: It would be great if forecasts from 10 different sources could be averaged.
Yeah, someone has already done this

We have already talked more than once about precipitation, its quantity and types. But it would be nice to understand this issue in more detail - it is very important!

All water falling from clouds in the form of rain, snow or any other form is called precipitation. Their quantity is measured in millimeters of the thickness of the layer of water that they would form on the surface of the earth if they did not spread, seep or evaporate. This quantity is measured over a specific period of time - per day, month or year.

To measure the amount of precipitation, rain gauges are used - reservoirs (usually metal barrels) in which precipitation that falls on the ground is collected. certain area(for example, using a funnel with an area of ​​one square meter). At the end of the observation period, the amount of water accumulated in the reservoir is measured and converted into units of thickness of the corresponding layer.

Instrument for measuring precipitation

For example, if 200 liters of water have accumulated, this means that the layer thickness will be 200,000 cubic centimeters / 10,000 square centimeters = 20 centimeters = 200 millimeters.

But water can evaporate from a barrel, too? Of course, especially in hot weather. And if our rain gauge is installed somewhere far from housing, and meteorologists come to it only once a month to find out how much precipitation has fallen in this place, are they mistaken? No, and to avoid mistakes, they came up with a funny way. A little oil (for example, machine oil) is poured into the barrel. It is lighter than water and therefore, when water enters the barrel, it spreads over its surface, forming a thin film. And an oil film of negligible thickness hides the water underneath.

Why are precipitation different?

Under certain conditions, water vapor in the air begins to turn into water - condense. At the same time, small droplets of water appear, still so light that they do not fall to the ground, but already so large that they can be seen. Fog or clouds appear. Further events can develop in different ways.

Typically, raindrops are about one millimeter in size, less often up to five millimeters. This happens because large drops in flight are crushed into smaller ones. The formation of large droplets is associated not with the process of steam condensation, but with the process of sticking together of small cloud droplets. In addition, if water droplets and ice crystals simultaneously appear in a cloud, crystals (snowflakes) grow while the droplets evaporate.

If the air under the cloud has a temperature lower than HS, the snowflakes reach earth's surface. In the warm air they melt, turning into raindrops. In the mountains you can often observe how in the valleys it's raining, and the peaks are simultaneously covered with snow.

Associated with this phenomenon is an important geographical concept - the snow line (or border). This is the name for the altitudinal level above which temperatures are so low that the accumulation of snow and other solid precipitation prevails over evaporation and melting. The existence of a snow line determines the height of glaciers in the mountains. Above the equator, it is located at an altitude of about 4,600 meters at sea level (and only high mountains, like Kilimanjaro, reach it), in the Arctic it drops to 200–500 meters (and glaciers form even on very low mountains, such as Byrranga), and in the Antarctic it drops to sea level (and ice shelves form, as in the Ross Sea ).

One of the most dangerous species precipitation – freezing rain. It is usually observed with the onset of warm weather. atmospheric front during the cold season. First, snowflakes form in the stratus clouds above the front. Getting into warm air, they melt, and the resulting drops fall into the cold ground layers of air. If the temperature here is not very low, they reach the ground without freezing. But when they get on cold pavements, branches, wires, etc., they freeze on them with a crust. ice. If the air under the front is very cold, the drops freeze in flight, forming cereal(ice balls less than five millimeters in diameter) or hail(balls are more than five millimeters). Hailstones can reach the size of an orange, and the largest measured, which fell on September 3, 1970 in Kansas, weighed up to 750 grams and had a circumference of up to 0.5 meters! In India, in the New Delhi region, in April 1888, 246 people were killed by hail.

The amount of precipitation is one of the most important characteristics of the weather, along with air temperature, and, of course, knowing it for a certain area, you can predict the weather for the future, you can even track climate changes, if any. But how to measure precipitation?

With snow, everything is more or less simple: we take a ruler, immerse it in the snow to the ground - and get the amount of precipitation in millimeters. But this trick doesn’t work with rain! After all, water is immediately absorbed into the soil, and that which is not absorbed (say, gets on the asphalt) evaporates relatively quickly, so we won’t get accurate results this way, even if it comes to flooding... how to measure the amount of rain?

There are special devices for this.

One of them is a rain gauge. In fact, it is something like a bucket, only very large - 5 square meters in area. Rainwater enters such a vessel through a cone-shaped funnel - so that the wind does not distort the measurement results by blowing additional water into the vessel, or vice versa - blowing it out of there. This design is installed on a weather site at a height of 2 meters. Once a day, the collected rainwater from the rain gauge is poured into a graduated vessel and measured in millimeters. Every millimeter is a liter of precipitation per square meter.

There are also soil rain gauges, which are buried in the ground level with it, and also field rain gauges, which are graduated glass vessels that are placed in agricultural fields.

But it is not always and not everywhere possible to check the results once a day! In the taiga, tundra, mountains and other hard-to-reach places, you have to check the results once a week, or even ten days - during this time the water can evaporate and the result will be distorted. To work in such extreme conditions There are total precipitation gauges. In design, it differs little from a conventional rain gauge, but when it is installed, Vaseline oil is poured into it. As a result, when water is added to the vessel, petroleum jelly floats to the surface, covering its surface with a thin layer that prevents the water from evaporating, preserving it for measurement.

However, you can determine the amount of precipitation without approaching the device directly, if it is a radio precipitation gauge. Its sediment collection tank is installed in such a way that when filled, it turns over, the water is drained from it, and this activates a mechanism that turns on the radio transmitter. Its radio signal is recorded at the nearest weather station, or it is sent to a meteorological satellite.

Another instrument used by meteorologists to measure the amount of rain is a pluviograph. Rainwater is collected in a vessel with an area of ​​5 square meters. The bottom of the vessel is cone-shaped, and there are holes in it into which water drains and enters the chamber through a pipe. The chamber contains a hollow float connected to a metal rod. At the top of the rod there is a arrow on which the pen is mounted, and next to the camera there is a drum with paper tape. The water accumulating in the chamber raises the float, it sets the rod with the arrow in motion, and the pen draws a curve on the tape, which is used to determine the level of precipitation.

Precipitation measurement. Determination of precipitation quality.

Precipitation measurement.

The amount of precipitation that fell on the Earth's surface in a given place over a certain time is estimated by the thickness of the water layer (in mm). The amount of solid precipitation is measured by the thickness of the layer of water that melted solid sediment would form. One millimeter of precipitation corresponds to a layer of fallen water in the amount of 1 liter per 1 m2. The amount of precipitation is measured by special instruments - precipitation gauges, which are usually located at a distance of several kilometers from one another and record the amount of precipitation over a certain period of time, usually 24 hours. A simple precipitation gauge is a cylindrical bucket of a strictly defined cross-section with a round funnel, installed at a weather site. Rainwater enters it and flows into a special measuring glass. The area of ​​the measuring cup is also known, so a layer of water 25 mm thick in the measuring cup corresponds to 2.5 mm of precipitation. The design of the rain gauge provides protection from rapid evaporation of precipitation and from blowing out snow that gets into the rain gauge bucket. More complex measuring instruments continuously record the amount, intensity and timing of precipitation (pluviographs). The average annual precipitation over the entire surface of the Earth is about mm. In tropical latitudes, the average annual precipitation is at least 2500 mm, in temperate latitudes - about 900 mm, and in the polar regions - about 300 mm. The main reasons for differences in precipitation distribution are geographical position of a given region, its altitude above sea level, distance from the ocean and the direction of prevailing winds. On mountain slopes facing the winds blowing from the ocean, the amount of precipitation is usually greater than in areas protected from the sea by high mountains.

Analysis of precipitation.

The duration of the study was from 11/25/11 to 11/29/11

Location of the study: Saransk, South-Western district.

Weather conditions: there were short-term snowfalls, which became the object of study.

The water sample was taken within a week, or more precisely during the study period indicated above.

Determination of the quality of precipitation.

Organoleptic method for odor determination:

We determine the nature of the smell by the sensation of the perceived smell (earthy, chlorine, petroleum products, etc.).

Determination method:

We take snow from the rain gauge and wait for it to melt. According to this table

Odor intensity 0 points.

Organoleptic method for determining taste:

With this method we determine the character and intensity of taste and aftertaste.

Four basic types of taste: salty, sour, sweet, bitter

Determination method:

The nature of taste or taste is determined by the sensation of perceived taste or taste (salty, alkaline, metallic, etc.)

We took the test water into our mouths in small portions, without swallowing, and held it for 3-5 seconds.

We determine the intensity and character of taste and aftertaste at 20°C and evaluate it by five-point system(in the table).

According to the table, the intensity of taste is 2 points.

Photometric method for determining turbidity:

We determined turbidity immediately after sampling. The water is not very cloudy at first glance. It can be assumed that it is suitable for drinking.

Conclusion: the precipitation that fell in this area does not contain impurities or other chemical elements. But if we conduct a more thorough study in the laboratory, I think that impurities or other chemical elements will be found.

Author Yoelina Diona asked a question in the section Climate, Weather, Time Zones

What does precipitation in millimeters mean? and got the best answer

Answer from Helga[guru]
Precipitation is measured by the thickness of the layer of fallen water in millimeters.
Precipitation is measured by rain gauges, precipitation gauges, pluviographs at meteorological stations, and for large areas - using radar.

At meteorological observations Precipitation is characterized by the duration of its fall and intensity, as well as the amount expressed in the thickness of the layer of fallen water.
The amount of precipitation is expressed in millimeters of the layer of water that would be formed from precipitation if it did not evaporate, seep into the soil, or run off.
Numerically, the amount of precipitation in millimeters is equal to the number of kilograms of water spilled onto an area of ​​1 sq. meter, i.e. 1 mm = 1 kg/1 m2.
___________________________

But how can we quantitatively imagine what 1 mm of precipitation is?

Not many can correctly explain how much it is.
For example, how to imagine 1000 mm of precipitation on an area of ​​1 hectare.

Knowing that 1 hectare = 10,000 m2

This means that 1000 mm of precipitation on an area of ​​1 hectare is 10,000 liters (or 10,000 tons) of water

or 1000 mm of precipitation is 1000 liters of water per square meter!! !

Accordingly, 1 mm of precipitation is 1 liter of water per square meter!!!

Answer from yoery[guru]
there is such a thing - Molchanov’s precipitation gauge, that’s where precipitation is measured in millimeters, an ordinary measuring cup at the bottom

Answer from Plush cat[master]
According to meteorological instructions, a millimeter of precipitation is one liter of water per square meter. At all weather stations there are precipitation measuring buckets, from which the observer, at 09 and 21 hours GMT, pours the precipitation that has fallen over a 12-hour period into a special vessel, from which the true amount is measured. Solid precipitation, that is, snow, is melted and specialists measure the resulting water.

Answer from 3 answers[guru]

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