Hiding power, often referred to in the context of pigments and coatings, is a measure of a material's ability to obscure or conceal an underlying surface or color. It is particularly important in applications such as paint, where the effectiveness of the paint in covering a surface without requiring multiple coats is crucial for both aesthetic and economic reasons.

A hail spike is a weather phenomenon associated with severe thunderstorms. It occurs when large hailstones are expelled from a thunderstorm, often resulting in a radar signature that appears as a spike on Doppler radar images. This spike typically indicates the presence of significant hail, often larger than one inch in diameter, within the storm. Hail spikes are formed when strong updrafts within a thunderstorm carry moisture and ice particles upwards to higher altitudes, where temperatures are below freezing.

Raman amplification is a process that utilizes the Raman effect to amplify light signals, primarily in optical fibers and other photonic devices. The Raman effect is a phenomenon where incident light interacts with the vibrational modes of molecular structures, causing a shift in the light's wavelength due to energy transfer between the photons and the molecules.

Goniophotometry is a measurement technique used to assess the luminous and color distribution of light emitted from a source or reflected from a surface. The term is derived from "gonia," meaning angle, and "photometry," which refers to the measurement of light intensity. In goniophotometry, light measurements are taken at various angles, typically using a goniophotometer, which is an instrument that allows for precise positioning of the light source and the measurement device.

Geometric albedo is a measure of the reflectivity of a celestial body, such as a planet, moon, or asteroid, as observed from a specific geometrical configuration. Specifically, it defines the ratio of the brightness of the object when illuminated by a light source (usually the Sun) to the brightness of a flat, fully reflective surface (like a perfect diffuser) under the same illumination conditions.

The Gaunt factor is a dimensionless quantity that arises in the field of astrophysics and plasma physics, particularly in the context of radiative transfer and the calculation of opacity in stellar atmospheres and hot plasmas. It quantifies the effect of electron scattering on the intensity of radiation in a medium.

The Ewald–Oseen extinction theorem is a fundamental result in the field of electromagnetism, particularly in the study of light scattering and the interaction of light with small particles. The theorem addresses how the incident light field is affected when it encounters a particle, specifically regarding the scattering of light by the particle.

Coherent Anti-Stokes Raman Spectroscopy (CARS) is a nonlinear optical technique used to obtain information about the vibrational modes of molecules. It is primarily employed in fields such as chemistry, biology, and materials science to probe molecular structures and dynamics.

Anomalous diffraction theory is a concept in the field of wave optics and scattering theory, primarily applicable to the interaction of electromagnetic waves, such as light, with small particles. The term "anomalous" refers to the deviations from the standard diffraction patterns predicted by classical diffraction theory (e.g., Rayleigh diffraction) when the size of the scattering objects is comparable to the wavelength of the incident light.

Analytical light scattering is a technique used to study the size, shape, and distribution of particles, macromolecules, or colloids in a solution by measuring the scattering of light as it interacts with these particles. This method is based on the principle that when a beam of monochromatic light (usually from a laser) passes through a sample, the light is scattered in different directions by the particles present in the solution.

In computational complexity theory, PP stands for "Probabilistic Polynomial time." It is a complexity class that consists of decision problems for which there is a probabilistic Turing machine that can decide the problem with a certain level of accuracy.

Kubelka–Munk theory is a mathematical model used to describe the light scattering and absorption properties of diffuse systems, particularly in relation to paints, pigments, and other similar materials. The theory, formulated by Paul Kubelka and Franz Munk in the 1930s, provides a way to understand how light interacts with multi-layered and heterogeneous materials.

Forward scatter refers to the phenomenon where light, or other forms of electromagnetic radiation or particles, are scattered in a direction that is close to the direction of the incoming beam. This is often studied in various scientific fields, including optics, astrophysics, and particle physics. In the context of light scattering, forward scatter typically occurs when light interacts with small particles or molecules. The degree of forward scatter can provide information about the size, shape, and composition of the particles.

Scattering, absorption, and radiative transfer are key concepts in various fields including atmospheric science, astrophysics, climatology, and optics. Here’s a brief overview of each concept and the role of codes used to model these phenomena: ### 1. Scattering **Definition**: Scattering refers to the process by which particles deviate from a straight trajectory due to non-uniformities in the medium through which they are traveling.

Secular resonance refers to a specific dynamical interaction that occurs in celestial mechanics and relates to the long-term orbital evolution of celestial bodies, particularly in system dynamics involving planets, asteroids, and moons. Unlike regular resonance, which occurs at specific orbital periods, secular resonance involves the gravitational interactions between bodies whose orbital precession rates (the rate at which their orbits rotate or change orientation) are in a simple integer ratio.

The term "relative scalar" can refer to several concepts depending on the context in which it is used. However, it is not a widely recognized term in mathematics, physics, or other scientific disciplines. Here are a few interpretations that might fit: 1. **Scalar Quantities**: In physics and mathematics, a scalar is a quantity that is fully described by a magnitude (a number) alone, without any directional component. Common examples include temperature, mass, and speed.

In the context of special relativity, a Lorentz scalar is a quantity that remains invariant under Lorentz transformations, which relate the physical quantities measured in different inertial reference frames. To elaborate, a Lorentz transformation is a mathematical operation that accounts for the effects of relative motion at speeds close to the speed of light, specifically how time and space coordinates change for observers in different inertial frames.

Scalar physical quantities are those that have only magnitude and no direction. They are fully described by a numerical value and appropriate unit. Examples of scalar quantities include: - **Temperature**: Measured in degrees (Celsius, Fahrenheit, Kelvin) - **Mass**: Measured in kilograms (kg), grams (g), etc. - **Length**: Measured in meters (m), centimeters (cm), etc.

Scalar field theory is a theoretical framework in physics that describes fields characterized by scalar quantities, which are single-valued and have no directional dependence. In contrast to vector fields, which possess both magnitude and direction (such as the electromagnetic field), scalar fields are represented by a single numerical value at each point in space and time. ### Key Concepts: 1. **Field and Scalar Values**: A scalar field assigns a scalar value to every point in space.

Mohammad al-Massari is a Saudi dissident and activist known for his opposition to the Saudi government. He gained prominence in the late 1990s and early 2000s for promoting democratic reform and human rights in Saudi Arabia. Al-Massari has been vocal about issues such as political repression, lack of freedom of expression, and the need for reform in the Saudi political system.