Question

Give geographical reasons for the following
Tropical cyclones occur rarely in Brazil.

Hint:

Due to semi-arid climate, poor soil, and drought.

Answer 1

Step 1: Tropical Cyclones and Brazil’s Location

Tropical cyclones are intense low-pressure systems that develop over warm tropical oceans. They require high sea surface temperatures, abundant moisture, and stable atmospheric conditions. Although Brazil lies within the tropical zone, it is far less affected by cyclones than regions like the Bay of Bengal or the western Pacific.

Basin context: The South Atlantic Ocean, which borders Brazil, is historically one of the quietest ocean basins for cyclone formation.

Step 2: Why Brazil Experiences Rare Cyclones

The South Atlantic has relatively cooler sea surface temperatures compared to the Indian and Pacific Oceans. Since cyclones typically require sea temperatures of around 26°C or higher to intensify, the cooler waters of this region prevent such systems from developing.

Additionally, the presence of strong vertical wind shear—the change in wind speed and direction with height—disrupts cyclone organization, inhibiting their growth and persistence.

Step 3: Coriolis Force and Cyclone Formation

The Coriolis force, which imparts the rotation necessary for cyclone formation, is weak near the equator. Much of Brazil’s coastline lies close to the equator, where this rotational effect is insufficient to sustain organized cyclonic systems. As a result, tropical cyclones rarely form or reach the Brazilian coast.

Synthesis: The combined effects of cool sea surface temperature (SST), weak Coriolis force, and strong wind shear lead to the very low frequency of tropical cyclones in Brazil.

\[ \textbf{Tropical cyclones are rare in Brazil due to cool waters, weak Coriolis effect, and strong vertical wind shear.} \]