Weather and Climate – UPSC World Geography Notes

Weather pertains to brief alterations in atmospheric conditions, while climate encompasses prolonged observations of these weather patterns. Weather comprises the diverse elements constituting it and the interactions among them, giving rise to a spectrum of atmospheric conditions and weather events.

This article below delves into a discussion of elements like temperature, atmospheric pressure, wind, humidity, precipitation, cloudiness, visibility, duration of sunshine, and more.


  • Temperature, pressure, wind, humidity, and precipitation interact to influence atmospheric conditions.
  • These factors affect aspects like wind direction, velocity, insolation, cloud cover, and precipitation amount.
  • Elements such as temperature, pressure, wind, humidity, and precipitation are integral to both weather and climate.
  • The impact of these elements varies across different locations and time periods, often localized and temporary.
  • Descriptive terms like sunny, hot, warm, cold, or fine reflect the prevailing weather conditions based on dominant elements.
  • Weather refers to the short-term atmospheric state of a location, considering one or more of these elements.
  • Nearby locations, even with a short distance apart, may experience different weather conditions simultaneously.


  • Seasons, distinct periods within a year, exhibit similar weather conditions.
  • A season is characterized by specific weather conditions resulting from the tilt of the earth’s axis and its orbit around the sun.
  • This cyclical pattern of seasons repeats annually.
  • Temperate regions typically recognize four seasons: spring, summer, autumn, and winter, each lasting for three months.
  • In our country, three distinct seasons prevail: summer, winter, and monsoons.
  • The Indian Meteorological Department identifies four main seasons:
    • Cold weather season (December to February)
    • Hot weather season (March to May)
    • Advancing monsoon season or rainy season (June to September)
    • Retreating monsoon season (October to November)
  • Equatorial regions, with direct sun rays year-round, experience consistent temperatures, rendering seasons insignificant.
  • Coastal areas, influenced by oceans, exhibit reduced seasonal variations.
  • Polar regions observe only two seasons: a prolonged winter and a brief summer.


  • Climate is the collective average of prevailing weather conditions spanning seasons throughout the year across an extensive area.
  • The average climate is determined by calculating data collected over several years, typically around 35 years, covering a broader geographical region.
  • Rajasthan, characterized by hot and arid conditions, contrasts with Kerala’s tropical rainy climate, while Greenland exhibits a cold desert climate, and Central Asia experiences a temperate continental climate.
  • The climate of a region is generally regarded as relatively stable and enduring.

Elements of Weather and Climate

Weather is essentially a product of diverse elements and their interactions, shaping various atmospheric conditions and weather events. All-weather, in particular, is influenced by eight fundamental elements or factors.

The primary elements include

  1. Temperature
  2. Atmospheric Pressure
  3. Wind
  4. Precipitation
  5. Humidity
  6. Visibility
  7. Clouds
  8. Duration of Sunshine


  • Temperature gauges the amount of kinetic energy in the air, determining the perception of heat or cold.
  • Celsius, Fahrenheit, and Kelvin scales are widely used for measuring temperature.
  • Thermometers are devices designed for temperature measurement.
  • Kinetic energy is practically generated as air particles move or vibrate at specific speeds.
  • An increase in particle movement leads to a rise in temperature.
  • Conversely, a decrease in particle movement results in a drop in temperature.

Atmospheric Pressure

  • Another crucial aspect of weather involves air pressure, especially influential in establishing or altering atmospheric conditions.
  • It stands out as one of the key factors in accurate weather forecasting.
  • Air pressure, also referred to as barometric pressure, denotes the pressure formed by the weight of air in the Earth’s atmosphere.
  • The term “barometric pressure” is derived from the device used to measure air pressure.
  • Despite being imperceptible, air possesses weight due to its composition of nitrogen, oxygen, argon, carbon dioxide, and other gases in microscopic particles.
  • The gravitational force of the Earth induces pressure from the weight of these air particles.
  • As there is a greater amount of air above the ground-level air, the air pressure is higher.


  • Air movement, commonly known as wind, stands out as a primary catalyst for weather phenomena.
  • Wind plays a pivotal role in major and extreme weather events, including cold and warm fronts, cloud formation, thunderstorms, and hurricanes.
  • Defined as the large-scale movement of air from high-pressure zones to low-pressure areas in the atmosphere, wind shapes weather patterns.
  • The distance between low and high-pressure regions, coupled with variations in air pressure, dictates the speed and strength of the wind.
  • Wind speed is measured by an anemometer, while a wind vane, also known as a weather vane, determines the wind direction.


  • Precipitation encompasses water in various forms, created when water vapor condenses into a solid state and descends to the earth due to its increased weight, making it unable to stay airborne.
  • Examples of precipitation include rain, snow, hail, and graupel.
  • Evaporation and condensation are the fundamental processes leading to precipitation.
  • Rain Gauge:
    • A rain gauge is a tool designed to measure rainfall.
    • Functioning like a collecting device, it gathers rainwater and computes the quantity that falls within a specific time frame.


  • Humidity plays a dual role by affecting weather patterns and directly influencing our personal comfort.
  • It denotes the quantity of water vapor present in the atmosphere at a specific moment.
  • Water vapor results from the transformation of liquid water into a gaseous state through evaporation.
  • While the impacts of humidity are often palpable, they are generally invisible to the naked eye.
  • The hygrometer is an instrument designed to measure humidity, not wind speed.


  • Visibility is the measure of how well an object can be seen over a specific distance.
  • This measurement becomes crucial in the presence of conditions like mist, haze, fog, and freezing drizzle, as they can substantially reduce visibility.
  • The importance of measuring visibility is occasionally underestimated, particularly in environments where clear visibility is essential, such as airports and harbors, where it directly impacts safety.
  • Instrument for Measuring Visibility:
    • Instruments like visibility sensors, including the “forward scatter sensor,” are employed to gauge visibility.


  • Clouds are composed of water droplets or water in different states, like ice and snow crystals, forming when water vapor undergoes a transition from a gaseous state.
  • Identifying specific cloud types and understanding their associated weather can be highly beneficial when assessing weather conditions solely through visual observations.
  • Instruments for Measuring Clouds:
    • Meteorologists utilize modern tools such as weather satellites and radars to comprehensively analyze clouds.
    • Satellite and radar imagery allows for reliable measurement of cloud density, moisture content, temperature, and movement.

Duration of Sunshine

  • The duration during which the Earth’s surface is directly exposed to solar radiation is referred to as sunshine duration, also known as sunshine hours. This metric measures the amount of sunlight received over a specific period, typically in hours per day or year.
  • Sunshine duration significantly influences various meteorological elements, contributing to overall weather patterns.
  • Its impact is more potent and influential than might be initially perceived.
  • Instrument for Measuring Sunshine:
    • Sunshine recorders, specifically Campbell–Stokes recorders, are employed to register the time the sun is visible.
    • Consisting of a spherical lens directing sunlight onto a specific type of tape, Campbell–Stokes recorders determine the duration of sunlight exposure.


  • These factors govern the global distribution of rainfall on Earth.
  • They play a crucial role in shaping human settlement patterns and influencing the development of diverse cultures.
  • The long-term weather patterns, known as climate, determine the overall livability of a location.
  • Historical shifts in climate, brought about by climate change, have impacted human migration patterns over time.

Historical alterations in these elements have taken place on both a global and local scale. Even today, there are ongoing changes, albeit imperceptible. As a result, these elements of weather and climate collectively exert diverse influences on the planet Earth.

Factors affecting Climate

Variations in temperature, humidity, and precipitation exist across different regions worldwide, shaping the lifestyles of inhabitants living under diverse climatic conditions. To comprehend these variations, let’s delve into the factors responsible for the climate differences in various places or regions.

Latitude or Distance from the Equator

  • Places near the equator are warmer due to the sun’s rays falling vertically.
  • Sunrays slant in temperate and polar regions, leading to lower temperatures.
  • Vertical rays are concentrated over a smaller area compared to slanting rays.
  • Vertical rays cover a shorter distance through the atmosphere before reaching the Earth’s surface.
  • Temperature is inversely proportional to latitude, with lower latitudes experiencing higher temperatures.
  • Malaysia, near the equator, is warmer than England, which is farther away.

Altitude or the Height from the mean sea level

  • Mountains are generally cooler than plains.
  • Despite being nearly on the same latitude, Shimla, at a higher altitude, is cooler than Jalandhar.
  • Temperature decreases with the elevation of a location.
  • On average, for every vertical rise of 165 meters, there is a decrease in temperature at a rate of 1°C.
  • Consequently, temperature decreases with an increase in height.

Continentally or the Distance from the Sea

  • Water exhibits poor heat conductivity, leading to a slower heating and cooling process.
  • Coastal areas benefit from the moderating effect of the sea, resulting in lower temperature ranges and higher humidity.
  • Inland locations, lacking the sea’s moderating influence, experience extreme temperatures.
  • Areas distant from the sea encounter broader diurnal (daily) and annual temperature ranges.
  • Despite their similar latitudes, Mumbai, being closer to the sea, has comparatively lower temperatures and higher rainfall than Nagpur.

Nature of the Prevailing Winds

  • Onshore winds transport moisture from the sea, resulting in rainfall along their path.
  • Conversely, offshore winds originating from the land are dry and contribute to evaporation.
  • In India, the onshore summer monsoon winds bring precipitation, while the offshore winter monsoon winds tend to be dry.

Cloud Cover

  • Regions with consistently clear skies, such as deserts, experience elevated temperatures even in shaded areas due to intense daytime sunlight.
  • During the night, the accumulated heat rapidly radiates back from the ground, creating a significant diurnal temperature range.
  • Conversely, in locations like Thiruvananthapuram with cloudy skies and substantial rainfall, the temperature range is notably smaller.

Ocean Currents

  • Oceanic movements occur as an effort to balance water temperature and density disparities between different locations.
  • Ocean currents represent substantial water flows, typically from warmer to cooler regions or vice versa.
  • Warm ocean currents elevate coastal temperatures and can bring rainfall, while cold currents lower temperatures and induce coastal fog.
  • Port Bergen in Norway remains ice-free in winter, benefiting from the warm North Atlantic Drift, while Port Quebec in Canada freezes during winter months due to the chilling influence of the Cold Labrador Current, despite its lower latitude.
  • Onshore winds, passing over warm currents, carry warm air to inland areas, elevating temperatures.
  • Conversely, winds over cold currents transport cold air inland, leading to the formation of fog and mist.

Direction of Mountain Chains

  • Mountain ranges serve as natural barriers for winds.
  • Moisture-laden onshore winds are compelled to ascend upon encountering the mountains, resulting in substantial rainfall on the windward side.
  • The descending winds on the leeward side lead to significantly lower rainfall.
  • The formidable Himalayas obstruct monsoon winds laden with moisture from penetrating into Tibet. Additionally, they prevent harsh polar cold winds from entering India.
  • Consequently, the northern plains of India receive ample rainfall, while Tibet remains a perpetually rain-shadow area with reduced precipitation.

Slope and the Aspect

  • On gentler slopes, where heat concentration is higher, the air temperature rises.
  • Steeper slopes experience lower temperatures due to reduced heat concentration.
  • Simultaneously, mountain slopes exposed to the sun are warmer than those in the shade.
  • The southern slopes of the Himalayas are warmer compared to the northern slopes.

The Nature of the Soil and Vegetation Cover

  • Soil characteristics are contingent on its texture, structure, and composition, and these attributes differ among different types of soil.
  • Stony or sandy soils exhibit good heat conductivity, while black clay soils rapidly absorb the sun’s rays.
  • Bare surfaces easily reradiate heat, contributing to the characteristic temperature fluctuations in deserts, which are hot during the day and cold at night.
  • Forested areas experience a narrower temperature range throughout the year compared to non-forested regions.

FAQs for Weather and Climate

Q. What is the fundamental difference between weather and climate?

Answer: Weather refers to short-term atmospheric conditions, while climate represents the long-term average of weather patterns in a specific region.

Q. How would you distinguish between climate and weather?

Answer: Weather is the day-to-day state of the atmosphere, whereas climate is the long-term average of these daily conditions.

Q. What do the terms “weather” and “climate” mean in meteorological terms?

Answer: Weather refers to the atmospheric conditions at a specific time and place, while climate refers to the average weather patterns over an extended period.

Q. Can you provide a clear definition of weather and climate?

Answer: Weather is the current atmospheric state, including temperature, humidity, and precipitation. Climate is the long-term average of weather patterns in a particular area.

Q. What are the key elements that differentiate weather from climate?

Answer: The duration and scope distinguish them. Weather is short-term and local, while climate is long-term and encompasses a larger geographical area.

Q. How would you define the elements that constitute weather and climate?

Answer: Weather elements include temperature, humidity, wind, and precipitation, observed over a short period. Climate involves long-term averages of these elements.

Q. In meteorology, what is the significance of understanding the difference between weather and climate?

Answer: Understanding the distinction is crucial for accurate forecasting, assessing long-term trends, and addressing issues related to climate change and variability.

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