Question

A broad trough of low pressure in equatorial latitudes is _______________.
A. El Nino
B. Jet stream
C. ITCZ
D. La Nina

Answer 1

Hint: Formation of pressure belts depend on dynamic controls, pressure gradient force and rotation of the earth. The air constantly moves from high-pressure areas to low-pressure regions.

Complete Answer: The sun shines vertically overhead in Equatorial Regions extending between 10 degrees North and South latitudes. The outer margins of this belt shift north and south of Tropic and Cancer and Tropic of Capricorn respectively due to the movement of the sun. This region receives high temperatures. There are no horizontal movements of winds as due to excessive heating winds approaching this belt to begin to rise vertically at the margins of the region. This region or belt is known as the zone of calms or Doldrums because of the absence of horizontal movement of winds.

Now let us examine the options
Option A - Warm water from the central Pacific Ocean replacing the cool Peruvian current off the Peruvian coast is called El Nino.
Option B - Jet streams refer to the current of air high over the Earth. They move toward the east at elevations of around 8 to 15 kilometres. They form where enormous temperature contrasts exist in the atmosphere.
Option C - The Inter-Tropical Convergence Zone is a belt of low pressure that encircles the Earth usually close to the equator where the trade winds of the Northern and Southern Hemispheres converge.
Option D - In Spanish the term ‘La Nina’ means “the little girl”, is an atmosphere pattern that portrays the cooling of surface ocean waters along the tropical west shoreline of South America. The counterpart of El Nino is La Nina.

Thus, the correct answer is option (C).

Note: There are other pressures belts that exist from the equator to the poles: Sub-tropical belt of high pressure, also known as horse latitudes which occurs between 25 degree - 35 degree North and south of the equator; the sub-polar low-pressure belts that occur between 60 degree - 70 degrees North and South of the equator and the polar high-pressure belt.