§ 29. The temperature (textbook)

§ 29. The temperature


1. Remember that is the source of light and heat Earth.

2. What is the relationship between the height of the Sun horizon and the amount of heat that enters the Earth's surface.


Heating air. Air atmosphere transmits sunlight to the earth's surface. However, it is rays are not hot. Heats Sun surface. And then from her hot air. Therefore, hth further from the earth's surface, the colder it becomes. Therefore, for an aircraft Temperature is very low. On the upper limits of the troposphere it falls to -56 0С.

Established that for each kilometer of altitude temperatures decrease on average by 6 0S. High in the mountains surface receives more solar heat than at foot. However, with high heat radiates faster. So when hiking in the mountains Temperature generally decreases. That is why the tops of high mountains are snow and ice.

Measurement air temperature. Everyone knows that the air temperature measured by a thermometer. However, be aware that improperly installed thermometer, such as the sun will not air temperature, and how C heated appliance itself.

At meteorological stations to obtain accurate air temperature thermometer placed in a special booth. Its walls lattice. This allows air to penetrate freely in it, while lattice protect the thermometer from sunlight. Budka set to 2 m height from the ground. Indicators thermometer recorded every 3 hours.

Record high temperatures on Earth 1958 0C was incorporated in Tripoli in northern Africa. The lowest temperature of -89.2 0C recorded on a scientific StationVostok in Antarctica. In Ukraine, the highest temperature of 40 0C observed in Kupyansk (Kharkiv region), the lowest - -43 0C in the Ukrainian Carpathians.

Daily process temperature. Sun heat the Earth during the day unevenly. Obviously, at noon when the sun is highest above the horizon, surface is heated most strongly. However, the highest temperature not observed at 12 th and at 14-15 hours. This is because the transmission heat from the earth's surface air takes time. In the afternoon, despite that the sun was falling toward the horizon, the air continues to heat yet within two hours of heated surface. Then the surface gradually and cooled under reduced temperature. The lowest temperature come before dawn. True, some days a diurnal variation of temperature can have significant margins.

So, the reason for temperature changes during the day is Surface light changed Earth's rotation around its axis.

Dependence temperature of the sun above the horizon height. To understand how temperature depends on the height of the Sun above the horizon, use the results Observing long midday shadows, which throws gnomon. In September, a shadow was same length. In October it was longer in November - still longer in the 20's of December - the largest. Since the end of December shadow again shortened. Thus, the change length of the gnomon shadow shows that during the year in the midday sun above the horizon happens at different altitudes. The shorter the shadow, the sun above the horizon and greater angle to the Earth's surface its rays. The greater the angle of incidence sunlight, the more heat gets surface and consequently higher Temperature. Then comes summer. The lower the sun above the horizon, the smaller angle of incidence of rays, the less heat gets lower surface and temperature. Then comes winter.

The time the sun at noon is the highest position in the firmament of the Northern Hemisphere occurred in June. Lowest position of the Sun in the firmament of the Northern Hemisphere - in December.

Annual process temperatures. During the year the surface is heated unevenly. Therefore, changing and air temperature. The annual course of temperature determine the average monthly air temperature. They can determine which month was the warmest and which - the coldest. Monitoring temperature air throughout the year show that in Ukraine, as in all Nordic hemisphere, the highest average monthly temperature is in JulyAnd the lowest - in January.

In the summer sun at noon is the highest position on horizon. During this period - the longest days, the surface is heated for a long time ago and the highest temperature. In winter - on the contrary.

Average temperature. Following our observation of changes in temperature air during the day, month or year, marks the highest (maximum) and lowest (minimum) temperature. But to compare temperatures of different nights, months or years, an average daily, monthly or annual temperature. Their calculated as an average number.

For example, average daily temperature receive from the ratio of the number of temperature measurements during the day. If during the time of observation were positive and negative temperature, then calculate separately the amount of positive and negative temperatures. Then higher amount is deducted from a smaller, but the difference is divided by the number of measurements. Near the result is put a sign tributed farm.

Average annual temperature are as amount of average monthly temperatures, divided by the number of months of the year.

A visual representation of the change in temperature give graphs of daily, monthly and annual course of air temperature (Fig.).

The amplitude of fluctuations in air temperature. The difference between highest and lowest air temperatures called amplitude of temperature (A).There are daily, monthly, annual amplitude.

For example, if the highest temperature during age was 17 0C, and lowest - 8 0C, the amplitude fluctuations equal to 9 0С (17 0 – 8 0 = 9 0). On the daily amplitude of temperature affects the nature of the earth surface (its called laying). For example, the amplitude of the oceans is only 1-2 0C on the steppes - 15-20 0C, and in deserts reaches 30 0C. At Cloudy daily amplitude decrease. In Ukraine, the largest daily temperature fluctuations are spring and summer of fair weather (7-10 0С).

The annual amplitude of temperature fluctuations depend mainly on latitude places: they are smaller near the equator (10C), significantly higher in middle latitudes (280 C at a latitude of Kyiv). On the same latitude, the farther from the ocean, the higher the annual amplitude.


FAQ task

1. The temperature near the earth's surface is 17 0C. Determine the temperature behind the aircraft, flying at an altitude of 10 km.

2. Tell us how the temperature during the day.

3. Why the highest daily temperature is coincides with the highest - meridian - the Sun above the horizon?

4. How should I dress when climbing of Goverlu if the air temperature near its bottom in 1915 0C. What will temperature on top? In calculating the relative difference of mind and absolute heights.

5. How does air temperature throughout the year?

6. Why Temperature depends on the height of the Sun above the horizon?

7. What is the annual amplitude of temperature fluctuations?