Portal field news

Portal field news

in ,

📷 | Brazilian photographer who fulfilled the wish of the newlywed "I want to take a picture with a rainbow in the background"

Photo The wishes of groom Alison and bride Priscilla ... (from Facebook)

A Brazilian photographer who fulfilled the wishes of the newlyweds, "I want to take pictures against the backdrop of a rainbow."

If you write the contents roughly
If there is no water vapor in the air, the refraction of light will not occur, so we have prepared the conditions for artificially producing a rainbow.

"Today, I prepared a completely different photo." Brazilian photographer Welliton Barbosa is a customer ... → Continue reading

 Daily Gendai DIGITAL

This is the website of the No. 1 evening newspaper "Nikkan Gendai".We will respond to everyone's "I want to know!" By slashing into the fact that the big media does not write in a hurry, hitting the article with the true intentions, anger, and questions of the masses from the reader's perspective.Popular serials such as columns for entertainers and athletes are also squeaky.

Wikipedia related words

If there is no explanation, there is no corresponding item on Wikipedia.

water vapor

water vapor(I'm sorry,steam(Also called)Wed Vaporization officialvapor.. It refers to the amount of water vapor in the air, especially the ratio of the amount of water vapor to the amount of saturated water vapor.(I.e.That.

Steam and steam

Water vaporcolorlessIt is a gas of and is invisible to the eyes.(I.e.Is a liquidWater dropletsIt is a mixed phase of air gas containing water vapor and water, but is visualized by water droplets. Other,(I.e.,hazeWhat appears to be white, such as steam, is air containing water vapor and water droplets out of water droplets.

Incidentally,steam(Yuge) cools in a place where the water vapor temperature is lowerCondensationHowever, it looks white due to water drops. For example,KettleWhen you see the steam coming out of the mouth when you boil the water, only the area near the mouth looks transparent. This portion is water vapor, and the mixed phase of water droplets and water vapor that has condensed due to the temperature of the gas being exposed to the outside air is steam.


VolcanoSprings naturallySpaCan be seen everywhereJapanThen,SpaEspecially since the water vapor of the hot spring suddenly cools in the air and turns into steam, which seems to rise up to white like smoke,YukemuriWas called and was familiar.

As an example,Nanki Tokugawa HistoryFour volumes of "Masuho no Susuki" stored inMuro-gun"KishuYumine hot springAs the explanation of the statement, "The gate is very hot,SteamIt rises like a fog in the vicinity, and it is more noticeable when there is no cloud, and it becomes rice if you boil food or soak white rice for a while, but radish is difficult to boil." There is.

Water and steam

When slowly heating water at room temperature under constant pressure[Annotation 1], A certain temperature (atmospheric pressure 760 mmHg Under 100 ℃) Changes to steam[Annotation 2].. The water is heatedevaporationHowever, the total volume increases, but the temperature remains constant during that time. After all the water has evaporated to a gas and then slowly heated further, the temperature of the steam begins to increase again.

When the steamed water is cooled, the steam follows the same path in reverse.CondensationThen it becomes liquid water. The above changes are common to not only water but also general substances. The temperature at which some water (liquid) begins to evaporateSaturation temperatureCall[Annotation 3], Conversely, its pressure, at its temperatureSaturation pressure (saturated vapor pressure)Call it. The saturation temperature of water at standard atmospheric pressure is 100 °C, and the saturation pressure of water at 100 °C is 760 mmHg = 1013.25 hPa. The saturation temperature rises with increasing pressure.

Saturated water (liquid)Saturated water(Saturated liquid other than water), steamSaturated steamThat is, water (liquid) at a temperature below the saturation temperatureSubcool water(Subcool liquid other than water), steam (gas) with a temperature above the saturation temperatureSuperheated steamCall it (same for other than water). Of subcooled water or superheated steamThermodynamic stateCan be specified by two state quantities (usually pressure and temperature).

Water containing steam bubbles and steam containing water droplets are generallyMoist steamIs called. If water and steam are in thermodynamic equilibrium (equal pressure and temperature), it is a mixture of saturated water (liquid) and saturated steam. If it is wet steam, the pressure is the saturation pressure and the temperature is the saturation temperature. In addition to pressure or temperature, the thermodynamic state of wet steam is(English edition) χ Can be specified using.

:Mass of gas,: Total mass

The higher the pressure, the more saturated gas vaporSpecific volume(Volume per unit mass) becomes smaller, while the specific volume of saturated water increases little by little because the saturation temperature rises, and the saturated water and saturated steam states merge into one point at a certain pressure. This stateCritical pointIt is not possible to distinguish between liquid and gas at pressures above the critical point (⇒Supercritical fluid). The critical point of water is 220.64bar (22.064 MPa; 217.75 ATM), temperature 373.95 Â° C (647.10 K), specific volume 0.0031700 m3/kg.

Slow cooling of moist steam in a closed vessel causes some of the steam to condense and the temperature and pressure to drop. When a certain temperature is reached while the wet steam is maintained, ice forms in a part of the wet steam and neither temperature nor pressure changes. This stateThree pointsIn the case of water, the temperature is 0.01 ° C (273.16 K) and the pressure is 0.006112 bar (0.0006112 MPa; 0.006032 atm).The triple point of water is used as the reference point for the temperature definition of the International System of Units.

When the triple point water is cooled further, the water changes to ice (coagulation), the temperature and pressure begin to drop again when the water runs out, and the vapor changes to ice (in general, the change in state between solid and gas).SublimationSay). Liquid water will exist in the limited pressure range between the triple point and the critical point. These things are properties common not only to water but to general substances.

Use of water vapor

Since steam is old,Steamed food,Steam bathHas been used for.Pressure cooker,AutoclaveAlso uses this almost.

Using water vaporSteam engineIt is,Industrial revolutionInPower sourcePlayed an important role as.modernThen.ReciprocatingSteadily declined,Steam power generation(Thermal power generation,Nuclear power)soSteam turbineIt is used to drive.

In addition, steamHeat mediumAndSteam heatingOr using high temperatureCleaning toolsThere is (steam cleaner).

注 釈

  1. ^ Slowly heat so that the temperature of the entire water becomes uniform. Strong heating raises the temperature of the water near the heated surface, which may cause vapor bubbles. The evaporation that causes vapor bubbles from the liquidboilingCall it.
  2. ^ The gas occupies the portion where air is removed, leaving only water vapor at the same pressure as the liquid.
  3. ^ Especially the saturation temperature at standard atmospheric pressure of 760 mmHgBoiling pointTo distinguish. The boiling point of water is 100 ℃ (99.9743 ℃ to be exact).Boiling pointThe term is not limited to standard atmospheric pressure, and may be used broadly to mean saturation temperature.


[How to use footnotes]

Related item


Back to Top