The third factor that affects temperature would be the distance from sea. This is mainly because the sea heats up relative quickly but loses heat slower as compared to land. As a result, the sea exerts a moderating influence on coastal areas, especially when prevailing winds blow onshore. At temperature latitudes, coastal areas are affected by moderating influences and them experience and maritime climate. This will mean that during the summer period, air heats up slowly and during the winter period, heat in the air is lost slowly. This will result in a small difference in temperature during the 2 seasons. This is a characteristic of a coastal area’s distance from sea. In temperate latitudes in inland areas, which are far away from the sea, they are not affected by moderating influences of the sea and are said to experience a continental temperature pattern. This will mean that during the summer period, air gains heat rapidly, while during the winter period, air is also lost quickly. This will result in an enormous difference of temperature during the two seasons. This is a characteristic of places that are inland.
The fourth factor will be the ocean currents. Ocean currents are flows of water surfaces in the ocean. Currents that originate from the equatorial regions that are called Warm Ocean currents while ocean currents that originate from the Polar Regions are known as cold ocean currents. A warm ocean current increases the temperature of coastal areas, when an onshore wind blows over it. A cold ocean current decreases the temperature of a coastal area especially when an onshore wind blows over it. An example of ocean currents affecting temperatures to prove my point will be in the North Atlantic Ocean. The cold Labrador Current decreases the temperature of St Johns during the winter and makes it freezing cold. The warm North Atlantic Drift increases the temperature of Valentia during January from 53 degrees N to 7 degrees Celsius.
The next factor that influences temperature is aspect. The definition of aspect is the direction of the slope of land relative to the sun. In tropical areas, such as in the equator, the midday sun is always high up in the sky and the angle of incidence is 90 degrees, thus the factor of aspect does not work in places like these, however, it does work in temperate areas as the angle of incidence is lower and there is an obvious change made by aspect. For example, in the Northern Hemisphere, the southern facing slopes have a relatively higher temperature as compared to the northern facing slope. This is because the southern facing slope is directly facing the Sun and is also sheltered from the cold winds of the North. The reverse happens in the Southern Hemisphere.
The sixth factor that affects temperature is humidity and cloud cover. Humidity is the state of the atmosphere in respect to the amount of water vapour. In high humidity areas, there is formation of more clouds as clouds are formed from condensation of water vapour into water droplets. A thick cloud cover is able to reflect incoming solar radiation so as to prevent excessive heating during the day. In the night, the thick cloud cover prevents the excessive cooling of earth by absorbing the outgoing terrestrial radiation, thus preventing them from escaping. This is also why the temperature only falls slightly. This explains the reasons why equatorial regions with high humidity and thick cloud cover, have a low diurnal temperature. In places with low humidity, little clouds are formed. Thus there will be little cloud cover and there can be maximum amount of incoming solar radiation that heats up the surface of the earth excessively. Temperature then rises rapidly during the day. In the night, as there is no cloud covers, heat is lost back into space rapidly as there is no interruption of outgoing terrestrial radiation. This results in the rapid decrease of the temperature in the night. This also explains why deserts that are low in humidity have such a wide diurnal temperature range.
Another factor would be land surface. For example, an area with vegetation is much cooler than a concrete surface. Trees and plants reduce the amount of incoming solar radiation from reaching the ground. The evaporation of moisture from leaves and twigs and branches and transpiration through stomata reduce cool the surroundings. In contrast, the concrete surfaces and buildings and urban areas absorb heat in the day and release them slowly in the night. This factor then branches into other sub factors. They are the albedo effect and urban microclimates resulting in an urban heat island. Albedo is the percentage of incident sunlight that is reflected. Albedo is the measure of the reflectivity of a surface. Objects that look bright reflect the light that fall on them and are said to have a high albedo. On the other hand, dark objects tend to absorb the light that falls onto them and have a low albedo. Albedo depends on a few factors and they are the colour of surface, the roughness and smoothness of the surface and the angle of incidence. As mentioned before, lighter surfaces reflect more than darker ones as they have a higher albedo. Darker objects tend to be warmer as they absorb the light that falls onto them. Land is smoother than sea water and generally has a higher albedo as compared to sea. There is also a trend of increasing albedo with increasing latitude. For example with a place of high latitude, the Polar Regions, where snow is abundant, have a high albedo. The other sub factor is urban microclimates. The larger the urban area, the greater the modification of the temperature will be. The urban heat island states that urban areas are warmer than rural areas. The urban heat island can he thought of as a patchwork of microclimates within the urban area. The heat island is the result of 5 key points. They are anthropogenic heat, height and arrangement of buildings, the nature of building materials, presence of water and presence of pollutants. Firstly, anthropogenic heat is heat by human, metabolic activity. It is also due to the heat released by vehicles, central heating and industrial activities. Densely packed areas release a lot of heat. The next point is the height and arrangement of buildings. In urban areas, especially cities, they are built vertically and close together. This point has a close link with albedo as the degree of warming of the surface depends on the reflectivity of the surface. In cities, radiation will be reflected off many surfaces and each one warming up in the process. The buildings are tall and close together and this brings up a new point on the sky view factor. Cities have a low sky view factor and generally mean that radiation is trapped in and there is little chance of radiation escaping. The orientation of buildings affects the long wave radiation/heat. The heat in cities released has a high chance of being intercepted by another surface and warming up. The way buildings are built in urban areas is an extremely vital point in determining the urban heat island and thus affecting temperature. The land surface and the building materials have a close link and concrete warms rapidly. In cities the surface is exposed and the surface area is larger, thus it is able to store the heat and released slowly in the night. Another point is the presence of water. Firstly, latent heat evaporates water but cannot be felt or measured with a thermometer. Sensible heat is heat that can be felt. In cities, there is presence of drains and sewers and they generally remove surface water. This result in a less demand of latent heat to evaporate thus the surplus of heat is converted to sensible heat that is used to warm up the atmosphere. Thus, urban areas are warm due to the absence of surface waters. The presence of pollutants is the next point in determining the urban heat island. Smoke and dust in cities reduce the amount of sunlight entering the city. The build up of carbon dioxide and ozone which are green house gases warms up the atmosphere and the pollutant dome which was already warmed by insolation in the first place. Thus, the pollutant dome re-radiates the heat back to the urban surface, prevents the escape of heat and adding on to the heat of the urban area.
Through all these points, each and every detail results in the variation of the temperature throughout earth. Some of the temperature difference is caused based on geographical locations while others occur naturally, some are also caused by human actions and pollutants released in the air. All these factors result in the ultimate change of temperature in the atmosphere.
Prepared by a High School Student