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  • What is climate?

    What is climate?

    What is climate?

    While the weather changes every day and a hot and humid day can be followed by a rainy one, the climate of a region remains the same for a long time. Thus, the summer season at the North Sea is generally cooler than in Freiburg and the winter season is rather cold and damp and not as snowy as in the Alps. The climate is driven by the sun, which heats up the air and gives rise to winds such as the trade wind. The oceans and the ocean currents also affect world climate, an instance of which can be seen in the way things turn topsy-turvy due to occurrence of 'El Niño'. The climate also undergoes long-term changes-the last ice age is a good example of this.

    How do oceans affect the climate?

    As the temperature of the oceans changes very slowly, the climate near the sea is quite equable and the air temperature fluctuates only negligibly. This equable climate is known as 'sea climate' or 'maritime climate'. The word 'maritime' is Latin and means 'related to the sea'. The winters are mild, and the summers are relatively cool and rainy. On the other hand, landmasses away from the sea get heated up by the sun very quickly. Hence, day and night temperatures fluctuate sharply, making the winters cold and the summers hot.

    Tracking down the climate

    You need: A plastic cup half filled with water, a plastic cup half filled with soil, a pen, a thermometer (0-40°C), a sheet of paper, a sunny day

    Do as follows: Place both the cups in the refrigerator for 10 minutes. Measure the temperature of the water and soil. Note down your findings. Now, place the cups in the sun for 20 minutes. Measure the temperature of the water and soil again. Compare the findings.


    What is a trade wind?

    The trade wind is a wind that blows throughout the year in the tropics, a broad belt around the equator. In the northern hemisphere, it blows from the northeast to the equator, and in the southern hemisphere, it blows from the southeast to the equator. The sun, being directly overhead, is very strong and heats up the air in the equatorial region. The warm air automatically rises up, reducing the atmospheric pressure and allowing the surrounding air to flow in towards the equator. This flow of air is called the 'trade wind'.

    What is the impact of ocean currents on climate?

    Hot or cold ocean currents affect the climate of the landmasses along their course. The Agulhas current, for instance, long prevented Portuguese sailors from reaching India. Ocean currents also affect temperatures all across the world. The current that brings warm water up the North Atlantic Ocean to the north-west European shores stops ice from forming near the coast and blocking ships from entering and exiting ports. In northern Canada, cold ocean currents freeze the soil all through the year. The cold Benguela current that runs off the coast of Namibia has created one of the driest deserts of the world-the Namib desert. This current does not allow the sea water to evaporate, and thus prevents the formation of clouds in the local sky.

    What is 'EI Niño'?

    'El Niño', which means 'the Christ Child' in Spanish, refers to a disturbance in the ocean current, which runs off the coast of Peru and which occurs every 3-8 years around Christmas. When distributed, the cold Humboldt current, which flows along the western coast of South America towards the north, is pushed back by warm water masses from southeast Asia. No one knows why this happens. The winds blowing over the Pacific also change dramatically during this disturbance; as a result, heavy rainfall and flooding occurs in places that were earlier dry, while the hot and moist regions experience such completely dry spells that fertile land dries up, crops wither, and people starve.


  • the temperature in the Sahara rises to 45°C during the day, while in the night it drops to just about 5°C?
  • earlier people used to throw 'bottle messages' in the ocean currents to find out the direction of flow?
  • around 12,000 years ago, in the last ice age, the gulf stream dried up? Consequently, the whole of Scandinavia was covered with ice.
  • around 500 years ago, there was a small ice age', which lasted for about 200 years? At that time, even the flat lagoons of Venice, which are usually quite warm, froze.

  • How did the ice age occur?

    There have been many ice ages in the entire history of the Earth. During these cold phases, the average temperature of the Earth dropped 5°C below the normal level and the polar regions were completely covered with ice. The last big cold period, known as 'ice age', ended around 10,000 years ago, with the thawing of the large glaciers that were several kilometres thick. It is not yet clear what causes an ice age. Researchers believe that the sudden change in the Earth's climate may be a result of some sort of a disturbance in the orbit of the Earth or a reduction in the heat of the sun reaching the Earth. Another theory suggests that, prior to the ice age, the continents might have changed positions and blocked or reduced the flow of warm currents from the equator to the poles, and thus allowed ice sheets to form in the region.