Factors affecting temperature

Question 1: What are the main factors that affect the temperature in a certain place? -Location, atmosphere, topography, ocean currents, vegetation, hydrology and human activities.

(1) location: including latitude location and land and sea location. ① Influence of latitude on temperature: The global temperature decreases from low latitude to high latitude. Such as heat, temperature and cold. (2) Influence of land and sea distribution on temperature: Due to the difference of thermal properties between land and sea, the temperature changes moderately in areas greatly affected by the ocean; On the contrary, it is affected by the land. For example, the temperate maritime climate is mild all year round, while the temperate continental climate is hot in summer and cold in winter.

(2) Atmosphere: including frontal activity and weather conditions: ① Frontal activity: mainly refers to the influence of cold front (warm front) on temperature before, during and after transit. For example, the cold front is controlled by the warm air mass before crossing the border, and the temperature is high; Cold front crossing, strong wind cooling; After the cold front passes through the border, it is controlled by the cold air mass and the temperature is low. Warm front is opposite. ② Weather conditions: It is cloudy during the day, and the temperature is often lower than that in sunny days due to the strong weakening effect of the atmosphere on solar radiation; Cloudy at night, because of the good insulation effect of the atmosphere, it is often warmer than a sunny night; On cloudy days, the temperature difference between day and night is often small, but on sunny days, it is the opposite.

(3) Terrain: Because the temperature in the troposphere decreases with the elevation (-0.6℃/ 100 m), the higher the terrain, the lower the temperature in the same hot zone. In addition, the tall terrain often blocks the cold air, so the temperature in mountain basins and valleys is often very high. At the same height, the temperature of sunny slope is slightly higher than that of shady slope.

(4) Ocean current: Warm current can increase temperature and humidity, while cold current can decrease temperature and humidity.

(5) Vegetation: mainly refers to vegetation coverage. In areas with high vegetation coverage, the temperature change is less than that of bare land because of its shielding effect on solar radiation and its influence on evaporation.

(6) Hydrology: Lake area, reservoir area, swamp, wetland, etc. Large heat capacity and low reflectivity to the sun, so the temperature difference is small.

(7) Human activities: urban heat island effect, atmospheric greenhouse effect, human afforestation and deforestation, building reservoirs and reclaiming land from lakes have great influence on the temperature.

Question 2: Factors affecting the temperature 3. The factors that affect the daily temperature range are:

(a) Latitude: The daily temperature difference decreases with the increase of latitude. This is because the change of sun height in a day decreases with the increase of latitude. The daily temperature difference in tropical areas is about 65438 02℃. The daily range of temperate zone is 8.0 ~ 9.0℃; The daily temperature difference of polar circle is 3.0~4.0℃.

(2) Generally, the daily temperature difference in summer is greater than that in winter, but in the middle and high latitudes, the maximum daily temperature difference in a year appears in spring. Because in summer, although the height angle of the sun is large, the sunshine time is long and the temperature is high during the day, the daily temperature difference in summer is not as large as that in spring because of the short day, short cooling time and high temperature at night in the middle and high latitudes.

(c) The daily temperature difference in low-lying areas (such as basins and valleys) is greater than that in convex areas (such as hills). The terrain is low and concave, the contact area between air and the ground is large, and the ventilation is poor. At night, it is often the place where cold air sinks and meets, so the daily temperature difference is large. On the other hand, because of high wind speed, strong turbulence, fast heat exchange and small daily temperature difference, the flat land is in between.

(4) Properties of the underlying surface Due to the differences in thermal characteristics and solar radiation absorption capacity of the underlying surface, the daily temperature difference is also different. The daily temperature difference on land is greater than that on the sea, and the farther away from the sea, the greater the daily temperature difference. The daily temperature difference of sandy soil, dark soil and dry loose soil is greater than that of clay, light soil and wet compact soil respectively.

(e) The daily temperature difference in sunny days is greater than that in cloudy days (rainy days), because the solar radiation is strong in sunny days, the ground temperature is strong, and the effective ground radiation is strong at night. The daily temperature difference in windy days is small.

Question 3: What are the factors that affect the glass transition temperature?

Amorphous polymers have a transition from glassy state to rubbery state-glass transition. This transition usually does not exceed a few degrees between temperature zones. But before and after the transformation, the modulus decreased by three orders of magnitude. In fact, it changed from a hard and brittle solid to a tough rubber. Therefore, glass transition is an important feature of polymers. The main reason for the formation of glassy state may be that the molecular structure of the polymer is asymmetric and it is impossible to form crystals; It may also be that there is not enough energy to rearrange the crystals. In addition, most polymers can only crystallize under certain conditions. At the same time, it is difficult for polymers to form 100% crystals, and there are always some amorphous crystals, so the glass transition is a common phenomenon of polymers, while the glass transition of polymers with less amorphous crystals is not obvious. 1. Determination of glass transition temperature During the glass transition of polymers, besides mechanical properties, other properties such as volume, thermodynamic properties and magnetism have changed greatly. Theoretically, the latter change is more important. The following is a brief introduction: 1, the change of volume is the most commonly used method to measure the glass transition temperature with dilatometer. Generally, the relationship between specific volume and temperature of polymer is measured. Extrapolating the straight lines at both ends of the curve to the intersection point of Tg (as shown in figure 1), it can be seen from the figure that the glass transition is related to the cooling rate: the cooling rate is fast. The obtained Tg is high; The slower the cooling, the lower the Tg. Similarly, the heating rate is fast or slow, and the Tg is also high or low. The reason for this phenomenon is that the system is not balanced. But it takes a long time (infinitely long) to reach the balance, which is impossible for experiments. The commonly used standard is 3℃ per minute. When measuring, the sample is often heated or cooled in a closed system, and the volume change is read by the rise and fall of the filling liquid level. This liquid can't react with polymer or dissolve or expand. Mercury is the most commonly used fluid, and some people use air to measure it, so that the change of pressure can be measured. Other characteristics related to volume can also be used for determination, such as the refractive index of the sample, X-ray absorption, etc. 2. Thermodynamic method Calorimetry is also a common method to determine the glass transition temperature. At Tg, the enthalpy changes obviously and the heat capacity changes suddenly. Since the appearance of differential thermal analysis (DTA) and differential scanning calorimeter, calorimetry has become more important. Like the change of volume, the change of enthalpy and heat capacity is also related to the rate: Figure 2 shows the relationship between specific volume (V) and enthalpy (H), and Figure 3 shows the relationship between volume expansion coefficient and heat capacity, with the phenomenon of "line lag". In the figure, curve 1 indicates slow cooling, curve 2 indicates normal cooling and temperature rise, and curve 3 indicates rapid cooling; Curves 1 and 3 are normal temperature rises. 3. Nuclear Magnetic Resonance (NMR) The method to study the glass transition of polymers by using the change of electromagnetic properties is NMR. Before the molecular movement begins, the protons in the molecule are in various states, so the nuclear magnetic resonance spectrum line reflecting the proton state is very wide. When the humidity increases and the molecular motion accelerates, the proton environment averages, the * * * vibration line narrows, and the linewidth changes greatly at Tg. Figure 5 shows the NNR line width of PVC (? H) change.

Question 4: What are the factors that affect the temperature? How do they affect the temperature? Factors affecting the temperature of a place: location, atmosphere, topography, ocean currents, vegetation, hydrology and human activities.

(1) location: including latitude location and land and sea location. ① Influence of latitude on temperature: The global temperature decreases from low latitude to high latitude. Such as heat, temperature and cold. (2) Influence of land and sea distribution on temperature: Due to the difference of thermal properties between land and sea, the temperature changes moderately in areas greatly affected by the ocean; On the contrary, it is affected by the land. For example, the temperate maritime climate is mild all year round, while the temperate continental climate is hot in summer and cold in winter.

(2) Atmosphere: including frontal activity and weather conditions: ① Frontal activity: mainly refers to the influence of cold front (warm front) on temperature before, during and after transit. For example, the cold front is controlled by the warm air mass before crossing the border, and the temperature is high; Cold front crossing, strong wind cooling; After the cold front passes through the border, it is controlled by the cold air mass and the temperature is low. Warm front is opposite. ② Weather conditions: It is cloudy during the day, and the temperature is often lower than that in sunny days due to the strong weakening effect of the atmosphere on solar radiation; Cloudy at night, because of the good insulation effect of the atmosphere, it is often warmer than a sunny night; On cloudy days, the temperature difference between day and night is often small, but on sunny days, it is the opposite.

(3) Terrain: Because the temperature in the troposphere decreases with the elevation (-0.6℃/ 100 m), the higher the terrain, the lower the temperature in the same hot zone. In addition, the tall terrain often blocks the cold air, so the temperature in mountain basins and valleys is often very high. At the same height, the temperature of sunny slope is slightly higher than that of shady slope.

(4) Ocean current: Warm current can increase temperature and humidity, while cold current can decrease temperature and humidity.

(5) Vegetation: mainly refers to vegetation coverage. In areas with high vegetation coverage, the temperature change is less than that of bare land because of its shielding effect on solar radiation and its influence on evaporation.

(6) Hydrology: Lake area, reservoir area, swamp, wetland, etc. Large heat capacity and low reflectivity to the sun, so the temperature difference is small.

(7) Human activities: urban heat island effect, atmospheric greenhouse effect, human afforestation and deforestation, building reservoirs and reclaiming land from lakes have great influence on the temperature.

Question 5: Factors affecting humidity Artificial lawn: solar radiation, wind, plant transpiration, temperature, soil water retention capacity, ground vegetation.

Shrub: solar radiation, wind, plant transpiration, temperature, soil water retention capacity. Ground vegetation.

Tall trees: solar radiation, temperature, soil water-holding capacity, ground vegetation, plant transpiration.

Wasteland: solar radiation, wind, temperature, soil water-holding capacity, ground vegetation, plant transpiration.

On the road: solar radiation, wind, temperature

Solar radiation, wind, plant transpiration, temperature, water storage capacity, ground vegetation.

The difference of these factors produces different humidity.