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It's expressed in meteorology
air
Hot and cold
degree
the
Physical quantity
It is called the air temperature, or air temperature for short. The international standard temperature measurement unit is
Degree Celsius
(° C).
Weather forecast
The temperature mentioned in the book refers to the temperature measured in the field with air circulation and out of direct sunlight
Air temperature
(usually measured in a screen). The maximum temperature is the highest value of the temperature in a day, generally appearing at 14-15; The minimum temperature is the lowest temperature in a day, usually before sunrise.
- Chinese name
- Air temperature
- Foreign name
- air temperature
- unscramble
- airborne temperature
- Standard temperature measurement
- Celsius scale ℃
- Measuring tool
- thermometer
- Scope of application
- meteorology
catalogue
- 1definition
- 2Temperature variation
- 3Temperature distribution
- 4Mean air temperature
- 5Extreme temperature
- ▪Extreme minimum temperature
- ▪Extreme maximum temperature
- ▪Extreme maximum and extreme minimum temperatures in China
- 6Maximum/minimum air temperature
- 7Influencing factor
- ▪Natural factor
- ▪Human influence
Weather forecast
The temperature in question is 1.5 meters above the ground in the observation field
shelter
The temperature measured on the thermometer is kept in good condition because of the thermometer
ventilability
And avoid direct sunlight, so it has a good representative. The difference in temperature is one of the main factors causing the difference in natural landscape and our living environment, and it is very closely related to our life.
Air temperature records can characterize the thermal characteristics of a place, which is indispensable in theoretical research, national defense and economic construction. Air temperature is one of the routine elements to be measured in surface meteorological observation. There are regular temperature (basic station observation 4 times a day, respectively 02, 08, 14, 20 four hours; Partial station
On the basis of
The actual situation is observed 3 times a day, respectively, 08, 14, 20 three times. Base station observation 24 times per day), daily maximum, daily minimum temperature.
Usually people use
Atmospheric temperature
The size of the value reflects the temperature of the atmosphere. For our country
Celsius scale
, expressed in degrees Celsius, read as degrees Celsius.
There are diurnal and annual variations in temperature.
The highest temperature is around 2 PM and the lowest temperature is around sunrise. In the northern Hemisphere, July is the hottest month and January is the coldest month on land, while August is the hottest month and February is the coldest month on sea. The southern hemisphere is the opposite of the northern Hemisphere.
Decreasing from low to high latitude, so
isotherm
Roughly parallel to the latitude line. The temperature of the sea and land is different at the same latitude. The summer isotherm protrudes in the direction of high latitude on land, and in the direction of low latitude on the ocean.
The snow and ice on the river melted
except
Daily mean temperature
There is also the average temperature of weather (5 days), ten days (10 days), month and year. To express the characteristics of temperature changes in different periods. The meteorological department will observe the temperature every six hours at 2:00, 8:00, 14:00, and 20:00 (Beijing time) every day, or every three hours at 2:00, 05, 08, 11, 14, 17, 20, and 23:00. For special needs (such as aviation), meteorological observation is even carried out at intervals of 1 hour and half an hour.
The average temperature of a month: the average of the average multi-day temperature in a month.
(3) Annual average temperature: The average multi-day average temperature (or multi-month average temperature) of a year.
Temperature trend chart
The lowest value of the minimum temperature in a given period of time (such as a day, month, year) in a calendar year. Depending on the given time period, there may be a day, month and year with extreme minimum temperatures. Such as:
The extreme minimum temperature of a month is selected from the minimum temperature of each day in the whole month. The extreme minimum temperature of a year is the extreme value selected from the daily minimum temperature of the whole year; The extreme minimum temperature of a day is the minimum temperature observed many times throughout the day.
If we consider the situation over many years, there are also extreme minimum temperatures on certain days, months and years. For example, the extreme minimum temperature of a certain day in many years is the extreme value selected from the minimum temperature of a certain day in the past year; The extreme minimum temperature of a certain month is the extreme value selected from the minimum temperature of a certain month in the past year; The annual extreme minimum temperature is the extreme value selected from the minimum temperature of the previous year.
Extreme maximum temperatures, also known as extreme maximum temperatures.
Refers to the highest value of the maximum temperature in a given period of time (such as a day, month, year) in a calendar year. Similar to the extreme minimum temperature, it can also be divided into the extreme maximum temperature of a day, month and year, and the extreme maximum temperature of a multi-day, multi-month and multi-year.
(1) The highest temperature extremes in China are in Xinjiang
Turpan
Before the founding of New China, Turpan had set a national record of 47.8 ° C. Later, on July 24 in 1953 and 1956, there was a high temperature of 47.6 ° C, and on July 13, 1975, the Turpan Civil Aviation Airport observed the current extreme maximum temperature in China - 49.6 ° C.
(2) Inner Mongolia Autonomous Region, China
The Greater Khingan Mountains
A temperature of -50.1 ° C was observed on January 16, 1922. It was the lowest temperature recorded before the founding of New China. After the founding of New China, the wealth of northern Xinjiang
Meteorological station
On January 20, 1960, the low temperature of -50.7 ° C broke the record of no crossing the river for the first time, and then on January 21, it set a new national record at -51.5 ° C. China's northernmost meteorological station, the Mohe Meteorological Station in Heilongjiang Province, measured a temperature of -50.9℃ in the early morning of December 27, 1968. On February 13, 1969, Mohe finally recorded the lowest extreme temperature in China's existing meteorological data -- -52.3℃.
The highest temperature is the highest value of the temperature in a day, which generally appears at 14-15, and the lowest temperature generally appears before and after sunrise.
Air temperature items and units for surface meteorological observation: regular air temperature, daily maximum and daily minimum air temperature. equip
thermometer
The weather station shall keep a continuous record of temperature. Take one decimal place in degrees Celsius (° C).
The temperature of a place is only caused by changes in solar radiation
Periodic change
In addition, there are non-periodic changes caused by the movement of the atmosphere. The change in actual temperature is the result of the joint action of these two aspects. If the former plays a large role, the temperature shows a periodic change; On the contrary, it shows an aperiodic change. However, judging from the general trend and in most cases,
Diurnal variation of temperature
And the periodicity of the annual change is still the main.
Heat balance
In various components, such as
Radiation difference
,
Latent heat
and
Sensible heat
Exchange, etc., are affected by different control factors. These factors such as latitude, season and other astronomical factors have obvious zonality and periodic characteristics. The nature of the underlying surface, the elevation of the terrain, and weather conditions, such as the amount of cloud cover and the degree of dry and wet atmosphere, are all affected
Non-zonality
Features. At the same time, the influence of these factors is not the same in different places, so the temperature distribution caused by the change of heat budget is also uneven.
A large number of artificial structures in the city, such as paved floors and various building walls, have changed the thermal properties of the underlying surfaces. Urban surface water content is less, more heat
Sensible heat
The form enters the air, causing the air to heat up. At the same time the city surface pairs
sunlight
The absorption rate is higher than that of the natural surface, which can absorb more solar radiation, and then make the air get more heat and increase the temperature.
(2) Cities
Air pollution
Motor vehicles, industrial production and a large number of people activities in the city have produced a large number of
Nitrogen oxide
,
Carbon dioxide
Dust, etc., these substances can be absorbed in large quantities in the environment
Thermal radiation
The energy, which produces the well-known greenhouse effect, causes further warming of the atmosphere.
(3) The influence of artificial heat source
Factories, motor vehicles, residential life, etc., burn a variety of fuels, consume a lot of energy, countless furnaces are burning, are emitting heat.
(4) The natural underlying surface in cities decreases
Urban buildings, squares, roads and so on have increased substantially, green Spaces, water bodies and other natural factors have decreased correspondingly, more heat release, less heat absorption, and relief
Heat island effect
The ability is weakened.
[1]
Air temperature is a measure of how hot or cold the air is
Physical quantity
Represents the average movement of air molecules
Kinetic energy
The size of. The unit of air temperature is usually expressed in degrees Celsius (° C)
Fahrenheit
(F) indicates one decimal place, and negative values indicate below zero.
Temperature records in China are generally measured in degrees Celsius (° C). The conversion relationship between Celsius and Fahrenheit is:
C=5/9 (F-32)
Air temperature measurement
Surface air temperature generally refers to the atmospheric temperature 1.25 to 2.0 meters above the ground. When measuring, in order to prevent
Solar radiation
right
Observed value
The temperature measuring instrument must be placed in a shelter or radiation shield, and the measuring element must be well ventilated.
observatory
The main instrument used by the station to measure the temperature of the air near the ground is a glass tube containing mercury or alcohol
thermometer
. Because the thermometer itself has a greater ability to absorb solar heat than the air, the reading indicated under direct sunlight exposure is often higher than the actual temperature of the air around it, so when measuring the temperature of the air near the ground, the thermometer is usually placed about 1.5m from the ground
shelter
Inside. These thermometers or thermometers are based on
Hydragenum
,
Alcohol
or
Bimetallic sheet
Made of thermal expansion and cold contraction properties as a sensor. The ground temperature mentioned by the meteorological department refers to the temperature in the shelter at about 1.5m above the ground.
Vertical thermometer
① Maximum temperature gauge
The highest temperature gauge
It is specially used to determine the maximum temperature at a certain time interval, and its structure is to handle a glass needle at the bottom of the ball and extend it straight to the capillary mouth to narrow the capillary mouth. When the temperature rises,
Hydragenum
It expands,
stress
Enlarging, forcing the mercury to squeeze through the narrow tube and rise. When the temperature drops, because there is not enough pressure to squeeze the mercury through the narrow tube to return to the sphere, the mercury column breaks at the narrow tube, so that the top of the mercury column above the narrow tube remains at the highest temperature indication that the thermometer has felt in the past period of time, and therefore the highest temperature can be measured.
② Minimum temperature meter
The minimum thermometer is specially used to determine the minimum temperature at a certain time interval, it uses alcohol as a temperature measurement liquid, put a cursor in the capillary, when the temperature rises, the alcohol expansion can rise over the cursor, and the cursor itself because the top of the tube wall has enough friction, can be maintained in place. When the temperature drops, the alcohol column shrinks to contact the tip of the vernier, due to the wine semen surface
Surface tension
The friction on the tube wall is greater than that of the cursor, so that the cursor will not break through the top of the alcohol column and drive the cursor down by the surface tension of the liquid surface. In other words, the cursor can only be lowered, not raised. Therefore, the degree of the cursor from the far end of the ball is the lowest temperature that has occurred in a certain time interval.
③ Wet and dry bulb temperature table
Wet and dry bulb thermometer
That is, an ordinary thermometer, its temperature measurement liquid is mercury, with an ordinary thermometer can determine the temperature change at any time.
Assmann
The ventilation dry and wet bulb thermometer was created by the German R Assmann in 1887. Two rod-shaped thermometers are placed in the ventilation duct with excellent radiation protection performance, and the mechanical or electric ventilation speed is 2.5 meters/second. The instrument has high measurement accuracy and is easy to use, and is commonly used for field temperature and humidity measurement.
It is an instrument that can automatically record continuous changes in temperature. The induction element is a bimetallic sheet, consisting of two pieces with a large difference in expansion coefficient
Metal welding
One end is fixed, and the other end is displaced with the change of temperature, and the displacement is close to the temperature
Linear relationship
. The recording system is composed of a recording clock and a recording pen. The recording pen is connected with an amplification lever and operated by an induction element.
It is made of the principle that the resistance of the wire is proportional to the temperature change. Commonly used metal wire platinum wire, copper wire, iron wire and other three, resistance value between tens to one hundred euros, of which platinum wire stability is the best, can be used as a standard thermometer. Resistance thermometers are suitable for telemetry.
There are several induction elements
Metal oxide
Mixed sintered conductor resistance, resistance value is usually tens of thousands of ohms, its
Temperature coefficient of resistance
Large, higher sensitivity
Metal resistance thermometer
However, the stability is slightly poor, and it is widely used in high-altitude telemetry.
Made of thermoelectric phenomenon, two metal conductors with different physical and chemical properties, A and B, are connected into a closed loop, called heat
couple
. When measuring, a contact of the thermocouple is placed in constant temperature conditions (such as ice water solution) called the reference end, and the other contact is placed on the object to be measured called the working end, the temperature of the two contacts is different, and the thermoelectromotive force will be generated, and the electromotive force is proportional to the temperature difference between the two contacts. The temperature difference electromotive force of copper-Constantane thermocouples commonly used in weather is only tens of microvolts, so in order to improve the sensitivity of temperature measurement, dozens of thermocouples are often connected together to form a thermopile. Thermocouple thermometers can be used for telemetry and are widely used in solar radiation instruments and microclimate observations.
Temperature distribution is commonly used
The isotherm diagram
Indicates. An isotherm is a line of points on the ground where the temperature is the same.
isotherm
The different arrangement reflects the different characteristics of temperature distribution. If the isotherm is sparse, it means that there is little difference in temperature between different places. Dense isotherms indicate a wide variation in temperature. The isotherm is flat, indicating that there are fewer factors affecting the temperature distribution. The bending of the isotherm indicates that there are many factors affecting the temperature distribution. The isotherm lines run parallel to the east and west, indicating that the temperature varies with
latitude
The difference is that latitude is the main factor. The isotherm is parallel to the coast, indicating that the temperature varies according to the distance from the sea, that is, the distance from the sea is the main factor, and so on.
There are three main factors affecting the temperature distribution, namely, latitude,
Sea Land
And the height. However, in the drawing of isotherms, the temperature values are often revised to the same height, that is, sea level, in order to eliminate the height factor and thus to show latitude, land and sea and other factors more clearly. The temperature distribution is different in different seasons of the year. January usually represents winter in the Northern Hemisphere and summer in the southern hemisphere, and July represents summer in the Northern Hemisphere and winter in the Southern Hemisphere. The characteristics of the average temperature distribution of the Earth surface in winter and summer can be analyzed as follows.
First of all, when you look at the global average temperature map, it's clear that
equator
Area temperatures are high, toward
The two poles
Gradually decreasing, that's a basic feature. In the Northern Hemisphere, isotherms are thinner in July than in January. This indicates that the temperature difference between north and south in the northern hemisphere in January is greater than that in July. This is because the direct sunlight in January is located in the southern hemisphere, and the high latitudes in the northern Hemisphere are not only
Noon sun altitude
It is lower, and the day is shorter, and in the northern hemisphere, the low latitude area, not only the noon sun is higher, but also the day is longer, so the northern Hemisphere in January north-south temperature difference is larger. The sun's direct rays in July are located in the northern Hemisphere, and the high latitudes have lower noon sun altitudes and longer days, while the low latitudes have higher noon sun altitudes and shorter days, so that the northern Hemisphere is north and south in July
Temperature difference
It's smaller.
Second, winter in the northern hemisphere
isotherm
It is roughly convex to the equator on the continents and to the poles on the oceans, while it is reversed in summer. This is because at the same latitude, the continental temperature is lower than the ocean temperature in winter, and the continental temperature is higher than the ocean temperature in summer. The southern hemisphere has a smaller land area and a larger ocean area, so the isotherm is relatively straight, and the isotherm also has a similar curvature to that of the northern Hemisphere when there is land. The influence of land and sea on temperature becomes clearer through the transport of heat by large ocean currents and air masses. Such as the most prominent
Warm ocean current
The warm air mass is the Gulf of Mexico warm current and the warm air mass above it, which lies north of 60 degrees north latitude
Norse
The average temperature in Sweden in January is 0-15 ° C, 10-15 ° C higher than that in Asia and the east coast of North America at the same latitude.
Prevailing westerly
At 40 degrees north latitude, in
Eurasia
Close to the Atlantic coast, the average temperature in January is above 15 ° C due to the influence of the ocean. On the east coast of Asia by land
Cold air mass
The average temperature in January is below -5 ° C. The average temperature difference between the east and west coasts of the mainland at the same latitude in January is more than 20℃. At 40 degrees north latitude
North America
The average temperature in January on the West coast is close to 10 ° C, while on the east Atlantic coast it is only 0 ° C, with a difference of 10 ° C. As for the influence of cold ocean currents on temperature distribution, it is also evident in South America and the west coast of Africa.
In addition, high mountains can block the flow of cold air and also affect the distribution of temperature. For example, China's
Tibetan plateau
, North American
The Rocky Mountains
European
Alps
Can prevent cold air from flowing south to east. Again, the maximum temperature zone is not located on the equator, but is 5-10 °N in winter and moves to about 20°N in summer. The average temperature in this area is higher than 24℃ in January and July, so it is called
Heat equator
. The position of the heat equator moves northward from winter to summer, because the position of the direct sun moves northward during this period, and there is a large amount of land in the northern Hemisphere, which makes the temperature strongly heated. Finally, the lowest temperatures in the Southern Hemisphere, both winter and summer, occur at the South Pole. In the Northern Hemisphere, only the lowest summer temperatures occur near the poles, while the coldest winter areas occur in eastern Siberia and Siberia
Greenland
Area.
Extreme temperature
The number of degrees and the region of occurrence are often not reflected in the average temperature map. According to existing records, the world's absolute lowest temperature occurred at
Eastern Siberia
Of Verkhoyansk and
Oymyakon
At -69.8 ° C and -73 ° C respectively, the new world minimum temperature of -90 ° C was recorded in the Antarctic in 1962. The world's absolute highest temperature occurred
Somalia
Within China, it is 63 ° C. Within China, the absolute highest temperature occurred in the Xinjiang Uygur Autonomous Region
Turpan
At 48.9℃. Absolute lowest temperature in Heilongjiang Province
Mohe County
It was -52.3 ° C on February 13, 1968.
Changes in temperature are still being felt
Atmospheric motion
So sometimes, the actual change in temperature situation is not as simple as the above cyclical changes. For example, after March, it is the spring season in the south of China, but often because of the cold air activities, there is a sudden cold phenomenon. Autumn, it is the autumn crisp time, often because
Warm air
The arrival of the sudden warming.
