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Author: Pigeon

Ice Pump

Ice Pump

An Ice Pump is a thermohaline mechanism of varying the thickness of an ice shelf. Salt is rejected as water crystallizes so the remaining liquid is saltier. The saltier water is more dense (i.e. has negative buoyancy) and sinks The salty water will melt the ice sheet through contact with it at deeper depths because it has a lower melting point The freshwater melt from the ice shell will be less dense and rise to shallower regions where it will refreeze…

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Signal Processing: Aliasing and Filtering

Signal Processing: Aliasing and Filtering

Aliasing describes the production of an artificially long wavelength due to slow periodic sampling of a periodic signal. To reproduce the signal accurately, the sampling frequency should be at least slightly larger than twice the highest frequency contained in the signal (a.k.a. the Nyquist frequency). For example, if the sampling rate is 2b then all frequencies less than b will not be aliased. Band Pass Filters will filter out certain wavelengths to allow the user to focus on different parts of…

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Where does a mineral get its color?

Where does a mineral get its color?

The color any object appears to be is actually the color most readily reflected away from it. The color of a mineral is is commonly due to the presence of trace elements and/or defects in the crystal structure and can be described in three broad categories. Crystal Field Transition: Electrons in the d orbital of transition elements (a.ka. chromophore elements) leap to higher energy levels when a light is shone upon them by absorbing some of the light at the…

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Salt Diapirism

Salt Diapirism

A diapir is region of lower density material (in this case salt) intruding into the overlying material. Salt Diapirs are formed through the slow process of evaporation, sedimentation, and compaction. A region experiences frequent flooding Subsequent evaporation will deposit salt The area is covered by later deposition where the overlying material will compact the deeper material. The density of the deeper sediment will increase while the density of salt is less affected by the pressure because of its crystal structure…

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Interpreting Stress-Strain Diagrams

Interpreting Stress-Strain Diagrams

A Stress-Strain Diagram gives you information on how a specific material deforms under an applied stress. Even though a stress-strain diagram will look slightly different for each material you test, there are certain diagnostic features that are good to keep in mind. Linear Elastic Regime: Stress is linearly proportional to strain up to the yield strength (red circle). Any deformation within this regime is elastic so the material will recover its original form if the stress is removed. The slope in the linear…

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