Climatic Controls

Latitude affects the intensity of sun rays. Therefore it is an important climatic control.

A change in latitude changes the angle at which the Sun’s rays strike the Earth. Near the Equator, rays are more direct, so solar energy is concentrated over a smaller area and temperatures are generally higher. At higher latitudes, rays are slanting and the same energy spreads over a larger area, producing lower temperatures. Features such as river depth are local conditions, not the main effect of latitude. Exam tip: Link latitude with the angle of solar rays and the distribution of temperature.

Near the Equator sun rays are more direct. Therefore temperature is generally higher there.

Altitude is a physical climatic control because it refers to the height of a place above sea level. As altitude increases, temperature generally decreases; therefore, mountainous areas are usually cooler than plains. Social, linguistic, and political factors are not direct physical controls of climate. Exam tip: Remember that altitude and temperature generally have an inverse relationship.

Sea water heats up and cools down more slowly than land. Therefore, places near the sea have a smaller difference between summer and winter temperatures, giving them an equable or moderate climate. In contrast, inland continental areas often experience more extreme temperatures. Exam tip: associate coastal areas with an ‘equable’ or ‘maritime’ climate.

Areas far from the sea have less maritime moderation. Therefore the difference between summer and winter may be higher.

Mountains act as barriers to moist winds and force the air to rise. As the air rises, it cools and condenses, producing rainfall on the windward slope. The opposite side may become a rain-shadow region, so rainfall is not the same on both slopes. Exam tip: This type of rainfall is called orographic or relief rainfall.

Moist air rises, cools and gives rainfall. Understand windward side as the slope facing the wind.

A rain-shadow area generally forms on the leeward side of a mountain. Moist winds rise along the windward slope, cool down, and produce rainfall there. After crossing the mountain, the air has less moisture, so the leeward side remains comparatively dry. The windward side receives more rainfall and is therefore not the rain-shadow area. Exam tip: associate a rain shadow with the leeward side of a mountain.

Warm and cold ocean currents can change thermal conditions along coasts. Link them with maritime climatic influence.

A warm current can make a coastal area relatively warmer. Ocean currents are counted among climatic controls.

Winds carry air and moisture from one place to another. Therefore pressure and wind systems affect climate.

Wind can bring moisture or thermal conditions from the area it comes from. Therefore wind direction is important.

The Himalaya acts as a massive mountain barrier. It largely prevents very cold winds from Central Asia from entering India, making winters in northern India less severe. It also forces monsoon winds to rise, helping them produce rainfall. India is not separated from the sea; the Indian Ocean lies to its south. Exam tip: Remember the Himalaya’s two key climatic effects—blocking cold winds and helping monsoon rainfall.

The Tropic of Cancer passes through central India. It helps understand India's latitudinal position.

Distance from the sea affects temperature and moisture. This creates differences between coastal and inland climates.

The correct answer is altitude. As altitude increases, air pressure and air density decrease, so temperature generally falls. Therefore, hill stations are cooler than nearby plains. Latitude also affects temperature, but for the temperature difference between hills and plains in the same region, altitude is the main control. Exam tip: remember that temperature decreases with increasing altitude.

Relief includes mountains, slopes and altitude. These can affect temperature and rainfall.

Latitude gives the angular distance of a place north or south of the Equator, so it indicates how far the place is from the Equator. As latitude increases, the Sun’s rays generally become more slanting and temperature decreases. Altitude also affects temperature, but it does not show distance from the Equator. Exam tip: For distance from the Equator as a climatic control, choose latitude.

At high altitudes, air pressure is lower and rising air expands and cools. Therefore, high regions such as Ladakh have low temperatures. Distance from the sea may increase the annual range of temperature, but altitude is the main reason such places are very cold. Exam tip: As altitude increases, temperature generally decreases.