One of the key "vital signs" of Earth's vegetation is the total green leaf area for a given ground area. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Terra and Aqua satellites collects global Leaf Area Index (LAI) data on a daily basis.

Explore using units in calculations with the Leaf Area Index (LAI). LAI is a ratio that describes the number of square meters of leaves per square meter of available land surface. Because of the units in the ratio, it is dimensionless

Explore using units for calculations with Normalized Difference Vegetation Index (NDVI). NDVI is a ratio of different light wavelength reflectance which can be used to map the density of green vegetation.

The fires in Greece during the summer of 2007 devastated large tracks of forest and ground cover in this Mediterranean region. Students analyze these data to determine the scale, area, and percentage of the forest impacted by of these fires.

Information from satellites if often used to display information about objects. This information can include how things appear, as well as their contents. Explore how pixel data sequences can be used to create an image and interpret it.

Be a Scientist: The GLOBE Program encourages you to use

Students can interact with NASA data to build a custom visualizations of of local, regional, or global plant growth patterns over time.  Use the Earth System Data Explorer to generate plots of satellite data as you develop models of this phenomenon.

See the following datasets in the Earth System Data Explorer:

• Monthly Leaf Area Index
• Monthly Normalized Difference Vegetation Index

Whether naturally occurring or set by humans, fires' effects reach far beyond ravaged lands. Combining satellite observations of fires with a computer model reveals the fires also affect air quality, health, and climate.

Identifying cause and effect relationships can help us make predictions about the function of natural systems and their impact on the world. These relationships, whether simple or complex, are vital for forecasting weather and predicting Earth events in new contexts.

The Earth's system exemplifies stability and change. Change and rates of change can be observed and quantified over very short or long periods of time and at various spatial scales (e.g., from landscape level to global processes).