Introduction to Geography

• Geography is the study of the Earth and its people

Branches of Geography

• Physical geography studies the Earth's natural features and processes
• Human geography studies human activities and their relationship to the environment
• Environmental geography studies interactions between humans and the natural environment

The Earth as a Planet

• The Earth is the third planet from the Sun in our solar system
• It is an oblate spheroid, nearly spherical but flattened at the poles and bulging at the equator
• The Earth's axis is an imaginary line passing through the North and South Poles, tilted at approximately 23.5 degrees relative to its orbital plane

Latitudes and Longitudes

• Latitude is the angular distance, measured in degrees, north or south of the Equator
  • Equator represents 0° latitude
  • Parallels of latitude are imaginary circles connecting points with the same latitude
  • Key parallels include the Equator (0°), Tropic of Cancer (23.5°N), Tropic of Capricorn (23.5°S), Arctic Circle (66.5°N), and Antarctic Circle (66.5°S)
• Longitude is the angular distance, measured in degrees, east or west of the Prime Meridian
  • Prime Meridian is the imaginary line running through Greenwich, England, representing 0° longitude
  • Meridians of longitude are imaginary lines running from the North Pole to the South Pole
• Latitude and longitude are used to determine the absolute location of any place on Earth

Maps

• A map is a representation of the Earth's surface or a part of it, drawn on a flat surface
• Essential elements include title, scale, direction, legend (key), and border
• A scale is the ratio of a distance on the map to the corresponding distance on the ground
  • Representative fraction (e.g., 1:100,000)
  • Verbal scale (e.g., 1 cm to 1 km)
  • Linear scale (graphical representation)
• Direction on a map is usually indicated by a north arrow
• A legend explains the symbols and colors used on the map

Types of Maps

• Physical maps show natural features like mountains, rivers, and deserts
• Political maps show boundaries of countries, states, and cities
• Topographic maps show elevation using contour lines
• Thematic maps show specific themes or patterns (e.g., population density, rainfall)

Weathering

• Weathering is the breakdown of rocks in situ (in place, without movement)
• Physical weathering involves mechanical disintegration of rocks:
  • Freeze-thaw weathering, exfoliation, abrasion
• Chemical weathering involves chemical alteration of rocks
  • Oxidation, carbonation, hydrolysis
• Biological weathering is the breakdown of rocks by living organisms
  • Root action, burrowing animals, microbial activity

Agents of Erosion

• Erosion involves the removal and transportation of weathered material
• Running water is a major agent of erosion, shaping landscapes through rivers and streams
• Glaciers are large masses of ice that erode the land through abrasion and plucking
• Wind is an agent of erosion, especially in arid and semi-arid regions
• Waves erode coastlines through hydraulic action, abrasion, and solution

Soil Formation

• Soil is a mixture of mineral particles, organic matter, water, and air
• Factors that influence soil formation:
  • Parent material, climate, topography, organisms, time
• Soil horizons are distinct layers in a soil profile
  • O horizon (organic layer), A horizon (topsoil), B horizon (subsoil), C horizon (parent material), and bedrock

Types of Soil

• Alluvial soil is fertile soil deposited by rivers
• Black soil (regur) is rich in iron and suitable for cotton cultivation
• Laterite soil is formed in tropical areas with high rainfall
• Red soil is formed from weathering of crystalline rocks
• Mountain soil is found in hilly and mountainous regions
• Desert soil is found in arid regions

Atmosphere

• The atmosphere is the layer of gases surrounding the Earth
• Composition of dry air: nitrogen (78%), oxygen (21%), argon (0.9%), and trace gases
• Layers of the atmosphere based on temperature:
  • Troposphere (0-10 km), Stratosphere (10-50 km), Mesosphere (50-85 km), Thermosphere (85+ km)
• The troposphere is where weather phenomena occur

Insolation

• Insolation is the incoming solar radiation received by the Earth
• Factors affecting insolation:
  • Angle of incidence, length of day, atmospheric conditions, latitude

Temperature

• Temperature is a measure of the degree of hotness or coldness
• Factors affecting temperature distribution:
  • Latitude, altitude, distance from the sea, ocean currents, prevailing winds, slope and aspect
• Isotherms are lines connecting places with equal temperature

Atmospheric Pressure

• Atmospheric pressure is the force exerted by the weight of the air above a given point
• Measured using a barometer
• Isobars are lines connecting places with equal atmospheric pressure
• Pressure belts:
  • Equatorial low, subtropical highs, subpolar lows, polar highs

Winds

• Winds are caused by differences in air pressure
• Winds blow from high-pressure areas to low-pressure areas
• Types of winds:
  • Planetary winds (trade winds, westerlies, polar easterlies)
  • Seasonal winds (monsoon winds)
  • Local winds (land and sea breezes, mountain and valley breezes)

Moisture in the Atmosphere

• Humidity is the amount of water vapor in the air
• Absolute humidity is the mass of water vapor per unit volume of air
• Relative humidity is the ratio of the actual amount of water vapor to the maximum amount the air can hold at a given temperature
• Condensation is the process by which water vapor changes into liquid water

Types of Rainfall

• Convectional rainfall occurs due to rising warm, moist air
• Orographic rainfall occurs when air is forced to rise over a mountain barrier
• Cyclonic rainfall occurs due to the convergence of air in a cyclone

Pollution

• Pollution is the contamination of the environment with harmful substances
• Air pollution is caused by emissions from vehicles, industries, and burning of fossil fuels
• Water pollution is caused by sewage, industrial waste, and agricultural runoff
• Soil pollution is caused by pesticides, fertilizers, and improper waste disposal
• Noise pollution is caused by traffic, construction, and industrial activities
• Measures to control pollution include reducing emissions, treating waste, and promoting sustainable practices

Natural Resources

• Natural resources are materials or substances that occur in nature and can be used for economic gain
• Renewable resources can be replenished naturally over time
  • Solar energy, wind energy, water, forests
• Non-renewable resources cannot be replenished easily
  • Minerals, fossil fuels (coal, petroleum, natural gas)

Conservation of Resources

• Conservation is the wise and sustainable use of resources
• Methods of conservation include:
  • Reducing consumption, reusing materials, recycling, using renewable energy sources, protecting natural habitats

Learn the basics of geography with a focus on physical, human, and environmental branches. Explore the Earth's shape, axis, and the importance of latitude and longitude in mapping and understanding our world. Understand Earth–Sun relationships, their impact on seasons, and time zones.