Geo-Ch.6

1. c. 2. b. 3. d. 4. d. 5. a

1. Frigid, Temperate, Torrid
2. less 3. dense
4. inverse, increases, decreases
5. Meteorologists, dimatologists

1. T 2. T 3. T 4. T 5. F

1. c. 2. e. 3. a. 4. b. 5. d.

1. The heat zones are divided on the basis of the amount of heat received. Earth is divided into three heat zones – the torrid, temperate and frigid zones.

2. Latitude, altitude, distance from the sea, prevailing winds, ocean currents and slope of land are the factors that affect temperature.

3. If the wind is an onshore one, then there is heavy precipitation on the windward side of the highland or mountain which is known as relief rainfall. However, as this wind descends the leeward side of the mountain, it gets compressed and warmed, and so condensation does not take place. The leeward side, thus, hardly receives any precipitation and is called the rain-shadow area.

4. Air pressure decreases with an increase in altitude. As we go higher up into the atmosphere, there is a decrease in the density of air and so, air pressure decreases. On an average, the rate of decrease is 1 mb for every 10 m increase in height above sea level.

5. Doldrums are a region of very low atmospheric pressure where hot air rises due to intense heating from the Sun. Because the air rises vertically, there is very little horizontal (surface) wind movement, making the area calm and windless. Location: The doldrums are located near the Equator, within about 5° north and 5° south latitude. This area is also known as the Equatorial Low Pressure Belt.

1. Temperature and altitude are closely related. As we go higher above sea level, the temperature decreases. This happens because air near the Earth’s surface gets heat from the land, which is heated by the Sun. Higher up, the air becomes thinner and cannot hold much heat. On average, the temperature falls by about 1°C for every 165 metres increase in height. That is why hill stations and mountains are cooler than nearby plains even during summer. Thus, places at higher altitude are cooler than places at lower altitude.

2.The Coriolis effect is the change in the direction of winds and ocean currents due to the rotation of the Earth. Because the Earth rotates, winds do not move in straight lines but get deflected. Ferrel’s Law tells us the direction of this deflection: In the Northern Hemisphere, winds turn towards the right. In the Southern Hemisphere, winds turn towards the left. So, the Coriolis effect is the cause of wind deflection, while Ferrel’s Law explains how the direction changes in each hemisphere.

3. Air pressure is not the same everywhere on Earth. It changes due to differences in temperature. Warm air becomes light and rises, creating low-pressure areas, while cold air becomes heavy and sinks, forming high-pressure areas. Because of this, the Earth has four main pressure belts: i. Equatorial low-pressure belt ii. Subtropical high-pressure belts iii. Subpolar low-pressure belts iv. Polar high-pressure belts Winds blow from high-pressure areas to low-pressure areas, affecting climate and weather conditions.

4.Planetary winds, also called permanent winds, blow throughout the year in a fixed direction due to pressure belts. These include: i. Trade Winds ii. Westerlies iii. Polar Winds Periodic winds change their direction during different seasons or times of the day. The most important example is the Monsoon wind, which changes direction between summer and winter. Land breeze and sea breeze are also periodic winds. Both types of winds influence rainfall and climate in different regions.

5.Precipitation means water falling from clouds to the Earth’s surface after condensation of water vapour. The main types are: i. Rain – Water falls in liquid form when temperature is above freezing. ii. Snow – Ice crystals fall in very cold regions. iii. Sleet – A mixture of rain and snow or frozen raindrops. iv. Hail – Small balls of ice fall during strong thunderstorms. Precipitation is very important as it supplies water and supports life on Earth.