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examBoard: Cambridge
examType: IGCSE
lessonTitle: Satellite Image Analysis
Satellite images are pictures of Earth taken from space. They're a key part of Geographic Information Systems (GIS) and help geographers study our planet from above. These images give us a unique view that we can't get from the ground, allowing us to see patterns, changes and connections across large areas.
Key Definitions:
Visible light images show what we would see with our eyes from space. They're good for seeing cities, forests and water bodies.
Infrared images detect heat and can show temperature differences. They're useful for tracking forest fires, ocean currents and urban heat islands.
Radar images can see through clouds and work at night. They're great for monitoring floods, ice and terrain.
Landsat: NASA's long-running program providing images since 1972, useful for tracking changes over time.
Sentinel: European Space Agency satellites that monitor land, ocean and atmosphere.
MODIS: Provides daily images of the entire Earth, good for monitoring large-scale events like wildfires.
Reading satellite images is a bit like being a detective - you need to look for clues and patterns to understand what you're seeing. Here are the key elements to look for:
Blue: Usually water (oceans, lakes, rivers)
Green: Vegetation (forests, farmland)
Grey/white: Urban areas, concrete, buildings
Brown: Bare soil or desert
Straight lines: Human-made features (roads, field boundaries)
Circular patterns: Irrigation systems, volcanic features
Irregular patterns: Natural features (rivers, coastlines)
Grid patterns: Urban areas, planned developments
Smooth: Water bodies, flat terrain
Rough: Forests, mountains
Shadows: Reveal height - longer shadows mean taller objects
Texture changes: Can show boundaries between different land uses
Satellite images aren't just pretty pictures - they help geographers solve real-world problems. Here are some ways they're used:
Deforestation monitoring: Tracking forest loss in places like the Amazon.
Pollution tracking: Identifying sources and spread of air and water pollution.
Habitat mapping: Identifying and monitoring wildlife habitats.
Climate change studies: Tracking ice melt, sea level rise and temperature changes.
Urban growth: Monitoring how cities expand over time.
Agricultural analysis: Assessing crop health and predicting yields.
Disaster management: Assessing damage after earthquakes, floods, or storms.
Infrastructure planning: Identifying suitable locations for new developments.
Satellite images have been crucial in tracking deforestation in the Amazon rainforest. By comparing images from different years, scientists can identify where trees are being cut down and how quickly.
Brazil's INPE (National Institute for Space Research) uses satellite data to produce annual deforestation reports. Their PRODES system has monitored the Amazon since 1988, providing evidence that helped reduce deforestation rates by 80% between 2004 and 2012.
When looking at these images, cleared areas appear as light patches against the dark green of the forest. Roads often appear as straight lines cutting through the forest, with deforestation spreading outward from these access routes in a "fishbone" pattern.
One of the most powerful uses of satellite imagery is comparing the same location at different times to spot changes. This technique helps geographers understand processes like urban growth, deforestation and climate change impacts.
When comparing satellite images from different dates, follow these steps:
Changes to look for include:
Wide coverage: Can view large areas at once.
Regular updates: Many satellites pass over the same area repeatedly.
Historical record: Archives of images date back to the 1970s.
Access to remote areas: Can view places that are difficult to reach on foot.
Objective view: Shows what's actually there, not what's reported.
Cloud cover: Clouds can block the view (except in radar images).
Resolution limits: Small features may not be visible.
Interpretation challenges: Requires skill to understand what you're seeing.
Cost: High-resolution images can be expensive.
2D view: Doesn't always show height well (though this is improving).
In your iGCSE Geography exam, you might be asked to interpret satellite images. Here's what you should be prepared to do:
When describing a satellite image in your exam, use this structure:
Always use compass directions (north, south, east, west) and relative terms (near, beside, surrounding) to describe locations of features.
Satellite image analysis is a powerful tool in modern geography that allows us to view and understand our planet from a unique perspective. By learning to interpret these images, you can identify physical and human features, track changes over time and understand geographical processes at local, regional and global scales.
Remember that while satellite images provide valuable data, they should be used alongside other geographical information sources like maps, field studies and statistical data for the most complete understanding of geographical issues.
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