Atmospheric pressure, pressure belts and winds - class-IX

Jet streams are some of the strongest winds in the atmosphere. There are two types of jet streams: Subtropical jet stream and polar jet stream. The streams that are centered at about 30$°$ latitude are subtropical jet stream.

The
word “monsoon” is derived from the Arabic word mausim, which means season. Basically,
it describes a seasonal wind shift over a region that is usually accompanied by
a dramatic increase in precipitation. Monsoon is experienced by Asia, North America, etc. Monsoon is the main source
of water. Monsoons are vital to agriculture and the economy.

Planetary winds (Trade, Westerlies, Polar Easterlies) blow consistently throughout the year. Monsoon winds are seasonal winds, not planetary winds.

Loo is strong, gusty, hot, dry wind blowing during the day over the north and northwestern India. It is especially strong in the months of May and June.

These are called tropical cyclones. It originates in the Bay of Bengal in India and in many other parts of the world.  Whenever these tropical cyclone occur they cause great loss of life and property due to heavy rains on the eastern coastal regions of India.

The doldrums (ITCZ) shift northwards during the summer months in the Northern Hemisphere, bringing the area into the influence of the trade winds.

The
planetary winds blowing between the tropics are known as trade winds. They are
found in the lower section of the troposphere near the earth’s equator. Trade
winds blow predominantly from the north-east in the Northern Hemisphere and
from the south-east in the Southern Hemisphere. More rainfall can be expected
within neighbouring landmasses if the trade winds become weaker.

True,

In the Northern Hemisphere, warm air around the equator rises and flows north toward the pole. As the air moves away from the equator, the Coriolis effect deflects it toward the right. It cools and descends near 30 degrees North latitude. The descending air blows from the northeast to the southwest, back toward the equator. Similarly, in the Southern Hemisphere, these winds blow from the southeast toward the northwest and descend near 30 degrees South latitude. If the direction of rotation changes the pattern will be a mirror image of the original, hence the Trade Wind in the southern hemisphere will blow from South West towards the equator.

Four States (Andhra Pradesh, Odisha, Tamil Nadu and West Bengal) and one UT (Pondicherry) on the East Coast and One State (Gujarat) on the West Coast are more vulnerable to cyclone disasters.

The climate of India is influenced by multiple factors including pressure systems, surface winds, the Coriolis force, upper air circulation, and western cyclonic disturbances.

The planetary winds which blows between the tropics are termed as trade wind. Trade wind move out from the sub tropical high-pressure belt towards equators. In different sections of their path, the condition of temperature, humidity, and density is not uniform. 

Tropical cyclone: it is a rapidly rotating storm with a low pressure centre, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain. The low pressure is due to rising warm air.

Monsoon is an example of seasonal wind. It is a seasonal modification of general planetary wind system. In summer, there is warm moist wind blowing from ocean towards land, while during the winter months a cold and dry wind originating on the land blows seaward. Monsoon winds are most powerful in India and China. In summer monsoon winds are known as south west monsoon, it is moist and brings a lot of rain. In winter it is known as north-east monsoon. As it comes from interior it is cold and dry. 

• The polar easterlies (also Polar Hadley cells) are the dry, cold prevailing winds that blow from the high-pressure areas of the polar highs at the North and South Poles towards low-pressure areas within the Westerlies at high latitudes.
• When air moves near the poles, cold temperatures shrink the air.
• Cold air subsides at the pole creating the high pressure, forcing a southerly (northward in the southern hemisphere) outflow of air towards the equator.
• This outflow is then deflected westward by the Coriolis effect, therefore these prevailing winds blow from the east to the west.
• Since the winds originate in the east, they are then known as easterlies.
• Unlike the westerlies in the middle latitudes, the polar easterlies are often weak and irregular.

Typhoon,

Easterly,

Northern Hemisphere,

West- East