Question
Compare the global distribution of temperature in January over the Northern and Southern Hemisphere of the earth.
Solution
The temperature distribution is generally shown on the map with the help of isotherms, the lines joining places having equal temperature.
The isotherms are generally parallel to the latitude. The deviation from this general trend is more pronounced in the month of January, especially in the Northern Hemisphere. As the land surface area is much larger in the Northern Hemisphere compared to that in the Southern Hemisphere, the effects of landmass and ocean currents are more pronounced.
In January, the isotherms deviate to the north over the ocean and to the south over the continents. This can be seen on the North Atlantic Ocean. The presence of warm ocean current, Gulf stream and North Atlantic drift make the North Atlantic ocean warmer and the isotherms bend towards the north. Over the land the temperature decreases sharply and the isotherms bend towards south in Europe. The effect of the ocean is quite evident in the Southern Hemisphere. Here the isotherms are more or less parallel to the latitudes and the variation in temperature is more gradual than in the Northern Hemisphere. The isotherm of 20°C, 10°C and 0°C run parallel to 35°S, 45°S and 60°S latitudes, respectively.
