Climate & Weather — Study Notes for UPSSSC PET

Overview

Climate and weather form a critical component of the Geography section in UPSSSC PET, with 3–5 direct questions typically appearing in the exam. Understanding the Indian monsoon system is particularly important since Uttar Pradesh's agriculture, water resources, and economy are directly tied to monsoon patterns. Beyond India, you must know the basic classification of world climate types and atmospheric phenomena like El Niño and La Niña that affect global weather patterns.

The key distinction to grasp: **weather** is the day-to-day atmospheric condition (temperature, humidity, rainfall on a given day), while **climate** is the average weather pattern over 30+ years for a region. Questions test your knowledge of monsoon mechanics, factors affecting Indian climate, major climatic zones in India and worldwide, and the impact of ocean-atmosphere interactions on weather.

Master the monsoon mechanism, Köppen climate classification basics, and the practical effects of El Niño/La Niña. These topics connect to agriculture, disasters, and current affairs, making them high-yield for PET preparation.

Key Concepts

• **Monsoon** derives from Arabic "mausim" (season); refers to seasonal reversal of wind direction. India receives 75–90% of annual rainfall during the southwest monsoon (June–September).

• **Indian climate is tropical monsoon type**, characterised by hot summers, moderate winters, and concentrated rainfall in 3–4 months. The Himalayas block cold Central Asian winds, while the Thar Desert creates low pressure attracting monsoon winds.

• **Four major seasons in India**: Winter (Jan–Feb), Pre-monsoon/Summer (Mar–May), Southwest Monsoon (Jun–Sep), Post-monsoon/Northeast Monsoon (Oct–Dec). Tamil Nadu receives most rain in the post-monsoon season.

• **Jet streams** are high-altitude westerly winds that influence monsoon onset and withdrawal. The subtropical westerly jet stream's northward shift in summer allows monsoon winds to enter India.

• **El Niño** is the warming of Pacific Ocean surface waters off South America, occurring every 2–7 years. It weakens the Indian monsoon, causing droughts. **La Niña** is the cooling phase, often bringing excess rainfall and floods to India.

• **Western Disturbances** are extratropical storms originating over the Mediterranean, bringing winter rainfall to North India (Punjab, Haryana, UP, Himalayas) — crucial for rabi crops.

• **Köppen Climate Classification** divides world climates into five major types: A (Tropical), B (Dry/Arid), C (Temperate), D (Continental), E (Polar). India has A, B, and C types across different regions.