Ans: B

Exp:

Statement 1 is correct: The distribution of atmospheric pressure over the globe is known as horizontal distribution of pressure. It is studied by drawing isobars at constant levels.  The isobars are lines connecting places with equal pressure. In order to eliminate the effect of altitude on pressure, it is measured at any station after being reduced to sea level for purposes of comparison.

Statement 2 is incorrect: The rate and direction of pressure changes are referred to as the pressure gradient. The spacing of isobars indicates the pressure gradient. The close spacing of isobars indicates a steep or strong pressure gradient, whereas the wide spacing of isobars suggests a weak gradient.

Reference: Chapter 10, Atmospheric circulation and weather systems, Fundamentals of Physical Geography, NCERT.

Ans: D

Exp:

The factors that affect the velocity and direction of the wind are as follows:

• Coriolis Force: It is a force resulting from the rotation of the earth about its axis. This force affects the direction of the wind. It deflects the wind to the right in the northern hemisphere and to the left in the southern hemisphere. The Coriolis force is directly proportional to the angle of latitude. It is at its maximum at the poles and absent at the equator.
• Frictional Force: The Frictional force between the wind and the terrain slows the wind by providing resistance to it. The rougher the terrain, the greater the frictional effect. Also, the stronger the wind speed, the greater the friction. 
• Air Pressure:  Air pressure affects wind direction by causing air to flow from high to low-pressure areas. The greater the pressure difference, the faster the winds.
• Pressure Gradient Force: The pressure gradient force (PGF) is a force that causes wind movement from high-pressure areas to low-pressure areas. The closer the isobars, the stronger the pressure gradient and the pressure gradient force.

Reference: Chapter 10, Atmospheric circulation and weather systems, Fundamentals of Physical Geography, NCERT.

Ans: D

Exp:

Statement 1 is incorrect: When the breeze flows from the land towards the sea, it is known as the land breeze.  At night, the land loses heat faster and is cooler than the sea. Hence,the pressure gradient is from the land towards the sea, resulting in a land breeze. It usually occurs during the night or early morning when the land air is cooler than the sea air.

Statement 2 is incorrect: The land heats up faster during the day and becomes warmer than the sea. Therefore, the air over the land rises, forming a  low pressure area, whereas the sea is relatively cool and the pressure over the sea is relatively high. Thus, the pressure gradient from sea to land is created, and the wind blows from the sea to the land as the sea breeze.

Statement 3 is correct: The pressure differences between land and sea generated by differential heating and cooling of the land and sea cause both land and sea breezes.

Reference: Chapter 10, Atmospheric circulation and weather systems, Fundamentals of Physical Geography, NCERT.

Ans: B

Exp:

Pair 1 is correct:  If an air mass is fully lifted above the land surface, it is called the occluded front. The fronts occur in middle latitudes and are characterised by steep gradients in temperature and pressure. They bring abrupt changes in temperature and cause the air to rise to form clouds and precipitation.

Pair 2 is incorrect:  When the front remains stationary, it is called a stationary front. A stationary front is a frontal system that forms when two air masses meet, but neither is strong enough to replace the other.

Pair 3 is incorrect: When the cold air moves towards the warm air mass, its contact zone is called the cold front. The cold fronts can produce sharper changes in weather and severe storms can occur. Whereas if the warm air mass moves towards the cold air mass, the contact zone is a warm front. Warm fronts cause moderate to gentle precipitation over a large area, over several hours and the passage of warm front is marked by rise in temperature, pressure and change in weather.

(Fig : Various fronts formed in Extra tropical cyclones)

Reference: Chapter 10, Atmospheric circulation and weather systems, Fundamentals of Physical Geography, NCERT.

Ans: C

Exp:

Extra-tropical cyclones are low-pressure systems developing in the mid and high latitudes. They are also known as Temperate Cyclones or middle-latitude cyclones.

Some of the features of the extratropical cyclone are as follows:

• They have a clear frontal system. 
• They cover a larger area and can originate on land or at sea. They affect a much larger area as compared to tropical cyclones.
• The extra tropical cyclones move from west to east, but tropical cyclones move from east to west. 
• The energy of a temperate cyclone depends on the densities of air masses.
• Isobars are usually ‘V’-shaped and the pressure gradient is low.
• In a temperate cyclone, rainfall is slow and continues for many days, sometimes even weeks.

Reference: Chapter 10, Atmospheric circulation and weather systems, Fundamentals of Physical Geography, NCERT.