Earth Science Movies
Earth science is a complex topic that requires the visualization and interpretation of many processes acting simultaneously. To better understand many of these phenomena, it can be helpful to create computer models of these processes. Here you can view movies of several simple computer models that are designed to illustrate the processes involved in six earth science concepts. I've also included one animation from a series of satellite images to illustrate weather processes.
Like most of the internet, this page is a work in progess, initial models are presented here, but not all of them are clearly documented, and some of the models used to generate these movies have... issues.
- Diffusion
Many processes in the earth system are controlled by diffusion. In this movie, we can watch the process of diffusion from two point sources. This is analogous to a contaminant or tracer injection into ground water, point sources of heat, or a variety of other phenomena. The top plot in this movie shows the x-y position of particles over time, while the bottom graph shows a histogram of x-positions for the two tracers. The red tracer is diffusing isotropically (uniform in all direction), while the black tracer is being transported by groundwater that increases velocity with increasing y-position. Both of these tracers are limited by a "wall" at y=-5. The end of this movie shows a graph of dispersion over time and the impact that this wall has relative to the expected random dispersion.
- Hurricanes
Hurricanes form as warm, moist air over an ocean rises. As the air mass rises the moisture contained within it condenses. The latent heat from the phase change of water from gas to liquid heats the air mass further causing it to rise further and more water condenses. This process pulls more air in from all sides to replace the air that has risen, if this air is also warm and contains lots of water it goes through the same process. This feedback loop causes a hurricane to increase in intensity over warm water (where there is an ample supply of warm moist air). Below is a movie of Hurricane Katrina before and after it struck the gulf coast. The hurricane starts in the bottom right as a tropical storm. After crossing Florida, the storm rapidly builds into a powerful hurricane as it feeds off the warm gulf waters. You will see the eye of the hurricane appear very rapidly shortly before the storm moves on land. When the storm moves over land it no longer has a supply of warm moist air. As a result the storm rapidly decreases in intensity.
- Ripples
Ripples occur in many places in the rock record and in modern stream beds, sand dunes, and beaches. The formation of ripples is a fascinating process that is controlled by the movement of the overlying air or water. In this movie you will watch an uneven surface evolve into a field of ripples moving downstream. The surface starts with completely random topography. As fluid above it picks up particles causes them to impact the surface downstream, ripples slowly form. As you watch, you will see the ripples evolve from short wavelength, low amplitude ripples to longer wavelength, higher amplitude ripples. You can also watch individual ripple crests connect to one another.
- Evolution of a Cinder Cone
Cinder cones are a type of volcano that spews rock out in violent eruptions. The shape of a cinder cone is due to distance these rocks can be thrown. In this movie you will watch a cinder cone develop (with occasional spurts of molten rock flying through the air). The landscape will start off completely flat, and build up as particles are ejected from a central vent. The surface of the cone will be marked periodically so that you can see the history of land surfaces. Eventually the sides of the cinder cone become too steep and particles begin rolling down the sides to maintain a shallow slope. This shows up in the historical surfaces as parallel lines at the same slope.
You can also watch this process occur in 3D here :
- Glaciers
Glaciers are gigantic, mobile sheets of ice. They are also one of the most effective erosion agents on earth. They move down hill extremely slowly, but with a tremendous amount of force. In this movie you will watch a valley/alpine glacier develop and the erosion of the landscape underneath the glacier as it evolves. You will watch this glacier form during cold periods and melt away during warm periods. The warm/cold cycle takes 100 thousand years (comparable to the real ice age cycle). The temperature slowly gets colder and colder, then rapidly increases at the end of an ice age (again, similar to reality). The temperature is illustrated by the equilibrium line altitude (ELA). The ELA is the elevation at which snowfall exactly balances the melting rate so the glacier is neither gaining or losing mass. Above the ELA, snowfall is greater than the melting rate, and the glacier is growing in size, below the ELA snowfall is less than the melting rate and the glacier is shrinking. During warmer periods the ELA is higher, during colder periods the ELA is lower. The increase and decrease in ice thickness is a balance between melting, snowfall, and the movement of ice downslope. This movement is a function of the local ice thickness and the slope. Erosion at the base of the bed is also a function of local ice thickness and ice movement rates. As a result, you will see more land erode near the middle of the glacier because this is where it is thickest.
- Settling rates
The rate at which a particle settles in a fluid is important to the development of a variety of sedimentary rocks. Most sedimentary rocks are what we call "normally graded" this means that the largest particles are on the bottom, and the smallest particles are on the top. This is because larger particles will settle faster than smaller particles. We also tend to see larger particles near the source of sediments and smaller particles further from the source. This is again due to settling velocities (and the energy required to transport a particle). Larger particles will settle faster as a result of friction (Galileo's famous experiments effectively removed friction). Thus, if we assume that all of these particles are traveling at similar horizontal velocities, they will travel less distance before reaching the bottom. This same theory can be applied the the rising of air bubbles in water (though with less accuracy as other processes are important here too). Here you will watch two movies, one modeling sediment deposition, and one modeling bubbles in a glass of tonic water. Note that in the sedimentation movie, the smaller (red) particles travel further and take longer to reach the bottom then the larger (blue) particles. Sediments are input at the top left of the model with a random size and horizontal velocity. This situation is roughly analogous to how a delta might form at the point a river enters a larger body of water. We would have to simulate several other processes if we wanted to reasonably model a delta.
I hope you have enjoyed these movies, if you have any comments, suggestions, or would like to use these movies, please contact me at gutmann@ucar.edu. In particular, I am interested in adding movies of these processes acting in the real world.