# Is spectral radiance same as intensity?

## Is spectral radiance same as intensity?

Radiance is used to characterize diffuse emission and reflection of electromagnetic radiation, or to quantify emission of neutrinos and other particles. Historically, radiance is called “intensity” and spectral radiance is called “specific intensity”. Many fields still use this nomenclature.

How do you calculate radiant flux?

In case of isotropic radiation (i.e., with constant radiant intensity), the total radiant flux is simply 4π sr times the radiant intensity. The radiant intensity is relevant, for example, for calculating how much optical intensity impinges a photodetector placed in some distance from the light source.

What is power per unit area?

In physics, the intensity or flux of radiant energy is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy. In the SI system, it has units watts per square metre (W/m2), or kg⋅s−3 in base units.

### What is solar radiation W m-2?

Solar Radiation (W/m2) This is the amount of sunlight hitting a horizontal surface, updated every five minutes at a particular site scattered about the state, in Watts per square meter.

How do you calculate electric field power?

As the source emits electromagnetic radiation of a given wavelength, the far-field electric component of the wave E, the far-field magnetic component H, and power density are related by the equations: E = H × 377 and Pd = E × H.

What is power flux?

In the area of high-frequency radiation the power flux density is the measure of the strength of the radiation in the far field. Its measuring unit is Watt per square metre (W/m²). It characterises the energy flowing per time unit through an area vertical to the distribution direction of the radiation.

## How is solar intensity measured?

An alternative method of measuring solar radiation, which is less accurate but also less expensive, is using a sunshine recorder. These sunshine recorders (also known as Campbell-Stokes recorders), measure the number of hours in the day during which the sunshine is above a certain level (typically 200 mW/cm2).