Related Experiment Video
Updated: Jun 27, 2026
06:48
Surface Mapping of Earth-like Exoplanets using Single Point Light Curves
Published on: May 10, 2020
Observed brightness distributions in overcast skies.
1Mathematics and Science Division, United States Naval Academy, Annapolis, Maryland 21402, USA. raylee@usna.edu
Applied Optics
|November 28, 2008
Summary
Mapping overcast cloud brightness is challenging due to motion and changing optical depths. Fisheye camera images offer a novel solution, revealing detailed brightness distributions and cloud thickness gradients.
Area of Science:
- Atmospheric Science
- Cloud Physics
- Radiometry
Background:
- Mapping cloud luminance and radiance distributions is difficult due to dynamic cloud motions and variable optical depths.
- Previous methods struggled to accurately capture the angular distribution of light under overcast conditions.
Purpose of the Study:
- To develop and validate a novel method for mapping overcast cloud brightness distributions.
- To investigate the location of brightness maxima in overcast skies.
- To estimate cloud thickness gradients using radiance measurements.
Main Methods:
- Utilizing fisheye images captured with a radiometer-calibrated digital camera.
- Calculating luminance and radiance maps from time-averaged fisheye images.
- Integrating measured radiances with MODTRAN4 simulations.
Main Results:
- Detailed maps of overcast brightness distributions were generated.
- The location of brightness maxima in overcast skies was clarified.
- Gradients in cloud thickness were estimated for observed overcasts.
Conclusions:
- Fisheye imaging provides an effective approach for detailed mapping of overcast cloud properties.
- This method aids in understanding cloud structure and radiative transfer.
- The technique offers insights into cloud thickness variations.
Related Concept Videos
01:02Flame Photometry: Overview
Flame photometry, also known as flame emission spectrometry, is a technique used for the qualitative and quantitative analysis of elements present in a sample using a flame as the source of excitation energy. The concept of flame photometry was realized in the early 1860s by Kirchhoff and Bunsen, who discovered that specific elements emit characteristic radiation when excited in flames. The first instrument developed for this purpose was used to measure sodium (Na) in plant ash using a Bunsen...
01:18Boundary Layer Characteristics
When a fluid encounters a solid surface, a boundary layer forms due to the interaction between the fluid's motion and the stationary surface. This phenomenon is characterized by a thin region adjacent to the surface where viscous forces dominate, influencing the fluid's velocity profile. The development of the boundary layer begins at the leading edge of the surface and evolves as the fluid moves downstream.As the fluid flows over the surface, friction between the fluid and the wall slows down...
01:16Flame Photometry: Lab
In a flame photometer, when a solution like potassium chloride is aspirated into the flame, the solvent evaporates, leaving behind dehydrated salt. This salt dissociates into free gaseous atoms in their ground state. Some of these atoms absorb energy from the flame, leading to their excitation. The excited atoms return to the ground state, emitting photons at characteristic wavelengths. Because only electronic transitions are involved, the resulting emission lines are very narrow. The intensity...
01:20Maxwell-Boltzmann Distribution: Problem Solving
Individual molecules in a gas move in random directions, but a gas containing numerous molecules has a predictable distribution of molecular speeds, which is known as the Maxwell-Boltzmann distribution, f(v).
This distribution function f(v) is defined by saying that the expected number N (v1,v2) of particles with speeds between v1 and v2 is given by
This distribution function f(v) is defined by saying that the expected number N (v1,v2) of particles with speeds between v1 and v2 is given by
01:13Attenuated Total Reflectance (ATR) Infrared Spectroscopy: Overview
Attenuated total reflectance (ATR) infrared spectroscopy is a powerful analytical technique used to study the composition of materials. It is widely employed in chemistry, materials science, forensic science, and other fields where sample characterization is required. ATR has several advantages over traditional transmission IR spectroscopy, including the requirement of little to no sample preparation and the ability to analyze a wide range of samples.
The ATR process begins by directing a beam...
The ATR process begins by directing a beam...
01:05Histogram
The histogram is a graphical representation in the x-y form of data distribution in a data set. The horizontal x-axis is labeled with what the data represents (for instance, distance from your home to school). The vertical y-axis is labeled either frequency or relative frequency (or percent frequency or probability).
A histogram graph consists of contiguous (adjoining) boxes. The heights of the bars correspond to frequency values. The graph will have the same shape with respective labels. The...
A histogram graph consists of contiguous (adjoining) boxes. The heights of the bars correspond to frequency values. The graph will have the same shape with respective labels. The...