There are many factors that influence weather and climate conditions in a region; such as, temperature, air pressure, wind, air humidity, and rainfall.
A. Air temperature
Air temperature or temperature is a condition that is felt on the surface of the Earth as hot, cool or cold. As you know, the surface of the Earth receives heat from the sun’s radiation in the form of electromagnetic waves. The radiation of the sun emitted is not entirely up to the surface of the Earth. This is because when it enters the atmosphere, the sun’s rays experience reflection, scattering, and absorption by materials in the atmosphere.
The percentage of the number of sunbathing and blending of sunlight by atmospheric particles is called albedo. When entering the atmosphere, about 7% of the Sun’s energy is directly blended back into space, 15% is absorbed by airborne particles and atmospheric dust, 24% is reflected by clouds, and 3% is absorbed by cloud particles. So, the percentage of albedo in the sun’s rays by the atmosphere is around 49%, while that which reaches the Earth’s surface is only 51%. The solar energy that reaches the surface of the Earth is then reflected back around 4%. So, the total amount of solar energy absorbed by the face of the Earth is around 47%.
The direct effect felt on Earth as a result of solar radiation is the difference in air temperature in various places. Factors that affect temperature differences include the following.
1.The coning angle of sunlight
The angle formed by the direction of the sun’s rays with the surface of the earth. The more upright the angle of arrival of the light, the stronger the intensity of the sun’s radiation and the higher the temperature of the air in the area. Conversely, the tilted angle of arrival of the beam, the weaker the intensity of irradiation and the lower the air temperature. Therefore, at midday, our air temperature feels very hot, while in the morning and evening our air temperature feels cool.
2.The duration of irradiation
The longer the irradiation of the sun the higher the air temperature in a place. For the Indonesian region with a tropical climate, where the periods of day and night are always relatively the same, which is around 12 hours, the difference in temperature during the summer and winter is not too striking. But in temperate and high latitudes where the difference in length between day and night in the summer and cold periods is very striking, the difference in air temperature between the two seasons is very high.
Table 1. The maximum duration of solar radiation during summer at some latitude
| Number | Latitude | Maximum Radiation Time (Daytime Period) |
| 1 | 0° | 12 hours |
| 2 | 17° | 13 hours |
| 3 | 41° | 15 hours |
| 4 | 49° | 16 hours |
| 5 | 63° | 20 hours |
| 6 | 66 1/2° | 24 hours |
| 7 | 67 1/2° | 1 month |
| 8 | 90° (Pole) | 6 months |
3. The height of the place,
The higher an area of sea level, the lower the air temperature will be. You certainly still remember the symptoms of thermometric gradients, where the average air temperature will decrease by about 0.5 ° C – 0.6 ° C each place experiences a 100-meter increase. Based on the results of the study, the average daily air temperature in the coastal areas of tropical regions such as Indonesia is around 26 ° C. Combining these two data, we can predict the average air temperature in an area using the following formula.
Information:
t ° C = average air temperature in the place we are going to calculate.
h = height of the place from the sea level (in meters).
4.Geographical conditions of the region.
For regions in Indonesia whose territory is an archipelago surrounded by sea, the difference in air temperature (temperature amplitude) daily is not very high. This is caused by the physical nature of water (water) which is slow to receive (absorb) heat, but it also slowly releases it.
This phenomenon is different from regions located in the middle of continents (land) far from the sea, such as Central Asia (for example in the Gobi and Tibet Desert), and the Sahara Desert. The difference in air temperature between day and night is very striking. During the day the air temperature is very high, while at night it is very low even below 0° C.
To measure air temperature somewhere a weather plane is used called a thermometer or thermography. There are two types of thermometers commonly used to measure air temperature, the maximum thermometer, and minimum thermometer.
The maximum thermometer consists of a tube containing mercury (mercury) because this liquid is very sensitive to rising temperatures, while the minimum thermometer is a glass tube containing alcohol which is very sensitive to temperature drops. Thermograph is a type of thermometer that automatically measures the dynamics of changes in temperature every time. On weather maps, places that have the same air temperature are connected to isotherm or isothermal lines.
B. Air pressure
The second factor that influences weather dynamics is air pressure, which is the energy that works to move air masses in a certain unit of the area from one place to another. Air pressure is strongly influenced by the level of density or density of air masses. The higher the air density, the higher the pressure. Unlike the density level which is directly proportional to air pressure, the temperature in an area is inversely proportional to the air pressure. The higher the air temperature, the lower the air pressure. This is because high temperatures cause the air in the area to expand and become tenuous.
A tool used to measure air pressure in a place called the Barometer, which uses a millimeter scale of mercury (mm Hg), millibars (MB), or atmosphere (atm). The comparison of the three scales is 1 atm = 760 mm Hg = 1013.25 MB. There are 3 types of barometers that we usually encounter at weather observation stations, namely as follows.
- Mercury Barometer, which uses a millimeter scale of mercury.
- Aneroid barometer, which uses the millibars scale.
- Barograph, which is an automatic barometer that records air pressure every time on barogram paper with a billable scale.
Various regions on the face of the earth have the same air pressure, but some are different. On maps, areas that have the highest air pressure compared to areas of high pressure, symbols (+) are usually used. Regions that have the lowest air pressure compared to other surrounding areas are called minimum pressure centers or low-pressure areas, usually (-) symbols are used. On weather maps, areas that have the same air pressure are connected with concentric lines called isobars.