Spectral bands are different ranges of wavelengths of light that are captured by a satellite sensor. These bands can include visible light, as well as other wavelengths outside of the visible range, such as infrared and ultraviolet. Each spectral band captures different information about the Earth's surface, allowing for analysis of various features such as vegetation, water, and urban development.
For example, the near-infrared band is useful for vegetation analysis, as healthy plants reflect more near-infrared light than unhealthy plants. The thermal infrared band can be used to detect heat signatures, allowing for the detection of forest fires or volcanic activity. The visible light band can be used to distinguish between different land cover types, such as forests, grasslands, and urban areas.
Spectral bands are often combined in a process called multispectral imaging, which can create a more comprehensive picture of the Earth's surface. Multispectral imaging can be used in a variety of applications, such as agriculture, environmental monitoring, and urban planning. For example, satellite imagery can be used to monitor crop health and predict yields, track changes in forest cover, and plan urban development projects.