Factors affecting climate

The climate at any location depends mainly on the following –

1. Surface features on land – altitude and elevation, nearness to oceans, distance from the equator, for example
2. Changes in the atmosphere– air pressure and wind currents
3. Changes in the oceans– ocean heat and ocean currents

Let us understand this with some examples –

Warm and cold fronts

The water heats up and cools down much more slowly than land does. Thus the air over land gets heated much faster than the air over water. This hot air rises, creating an area of low pressure on land. Relatively cooler air from the ocean blows into this low pressure, causing sea breezes near coastal areas. Such moving air masses are called Warm Fronts and Cold Fronts of air. They affect the speed and direction of winds, temperature, cloud cover, and level of precipitation, in coastal areas.

Sea breezes are also responsible for causing precipitation in the form of rain and thunderstorms. Cool air from the ocean is laden with water vapor, which evaporates on the warmer land, causing rainfall. In peninsular areas such as in Florida, sea breezes from the east and west collide to cause thunderstorms. Tropical regions nearer the equator receive intense sunlight resulting in higher temperatures there. They witness periodic storms, hurricanes, typhoons and cyclones, both on land and at sea.

Ocean currents

The ocean is the largest collector and storage space for solar energy. Due to its size, it absorbs huge amounts of heat. This heat causes currents in the ocean, much like in the air. Warm ocean currents raise the temperature of nearby lands while cold currents lower it. The warmth of the ocean eventually re-enters the rest of the earth’s systems and is responsible for reheating the atmosphere, evaporating water and even melting ice shelves on mountains.

Volcanic eruptions

Volcanic eruptions spew ash and dust particles in the atmosphere, reducing solar energy reaching the earth and consequently lowering temperatures in the region and even globally. Global precipitation also reduces as a result of volcanic eruptions.

El niño effect

Unusual warming of the surface of the eastern tropical Pacific Ocean has a disruptive impact on ocean temperatures, ocean currents, and weather over large parts of the earth. This is known as the El Niño Effect. As a result of the warming, low-level winds start blowing in the opposite direction, from west to east, shifting tropical storms and hurricanes eastward from the ocean to the west coast of South America. It results in greater precipitation in the southern parts of the United States.

Monitoring the weather

Climate forecasters rely on a variety of tools to study and keep track of weather patterns around the world. Some of these are –

1. Barometer to measure atmospheric pressure
2. Thermometer to measure air and water temperatures
3. Anemometer to measure wind speed and pressure
4. Psychrometer to measure relative humidity

Check Point

1. Where it rains more on a mountain range is called its –
   1. Leeward side
   2. Cold Front
   3. Windward side
   4. Warm Front
2. Difference in heating or cooling between land and water tends to cause –
   1. Warm or cold fronts
   2. Sea breezes
   3. Greater precipitation
   4. All of the above
3. Global climate can be affected by –
   1. Volcanic eruptions
   2. Greenhouse gases
   3. El Niño effects
   4. All of the above
4. Which of these are greenhouse gases?
   1. Methane
   2. Nitrogen
   3. Ozone
   4. Oxygen
5. A psychrometer measures ______.

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