Midterm Flashcards
Defined as the sun’s horizontal position angle, measured from the south.
Azimuth Angle
Solar position is _________ for any given time and location.
Absolutely predictable
Exterior illumination depends upon
> Solar position
Weather condition
Effects of local terrain
Cloud cover, unlike solar position, is only _________
Statistically predictable
The four basic sky conditions
> Solid overcast sky
Clear sky without sun
Clear sky with sun
Partly cloudy sky
Overcast Sky is sometimes called
Commission Internationale de I’Eclairage sky
Its has a non-uniform brightness distribution, increasing from horizon to zenith in approximately a 1:3 ratio
Overcast Sky
It is the ratio of indoor illuminance to available outdoor illuminance.
Daylight Factor
The two source components of Horizontal Illuminance
> Diffuse illumination from the sky
>Direct sunlight
It is valued from the sun as a function of solar altitude, when combined with proper portion of diffuse illuminance
Horizontal Illuminance
It is important for determining the daylight contribution of vertical, elements in skylights and it is also a major component of interior daylight.
Vertical Surface Illuminance
It is defined as the horizontal angle between a vertical plane containing the sun and a plane perpendicular to the vertical surface.
Bearing angle
A type of sky that is difficult to express mathematically because of its infinite variability of conditions.
Partly Cloudy Sky
The illumination from a partly cloudy sky is higher than of a clear sky by ___ to ___ because of additional reflected sunlight from cloudy edges.
10 to 15 %
It is the radiant power at each wavelength or band of wavelength in the visible region
Spectral power distribution
