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The hour angle at any instant is the angle through which the earth has to turn to bring the meridian of the observer directly in line with the sun's rays. Check FAQs
ω=acos(-tan(Φ-β)tan(δ))
ω - Hour angle?Φ - Latitude Angle?β - Tilt Angle?δ - Declination Angle?

Hour Angle at Sunrise and Sunset Example

With values
With units
Only example

Here is how the Hour Angle at Sunrise and Sunset equation looks like with Values.

Here is how the Hour Angle at Sunrise and Sunset equation looks like with Units.

Here is how the Hour Angle at Sunrise and Sunset equation looks like.

2.0909Edit=acos(-tan(55Edit-5.5Edit)tan(23Edit))
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Hour Angle at Sunrise and Sunset Solution

Follow our step by step solution on how to calculate Hour Angle at Sunrise and Sunset?

FIRST Step Consider the formula
ω=acos(-tan(Φ-β)tan(δ))
Next Step Substitute values of Variables
ω=acos(-tan(55°-5.5°)tan(23°))
Next Step Convert Units
ω=acos(-tan(0.9599rad-0.096rad)tan(0.4014rad))
Next Step Prepare to Evaluate
ω=acos(-tan(0.9599-0.096)tan(0.4014))
Next Step Evaluate
ω=2.09093001937086rad
LAST Step Rounding Answer
ω=2.0909rad

Hour Angle at Sunrise and Sunset Formula Elements

Variables
Functions
Hour angle
The hour angle at any instant is the angle through which the earth has to turn to bring the meridian of the observer directly in line with the sun's rays.
Symbol: ω
Measurement: AngleUnit: rad
Note: Value should be greater than 0.
Latitude Angle
Latitude Angle is defined as the angle between the sun's rays and its projection on the horizontal surface.
Symbol: Φ
Measurement: AngleUnit: °
Note: Value can be positive or negative.
Tilt Angle
Tilt Angle is the angle between the inclined slope and the horizontal plane .
Symbol: β
Measurement: AngleUnit: °
Note: Value should be greater than 0.
Declination Angle
The declination angle of the sun is the angle between the equator and a line drawn from the centre of the Earth to the centre of the sun.
Symbol: δ
Measurement: AngleUnit: °
Note: Value can be positive or negative.
cos
Cosine of an angle is the ratio of the side adjacent to the angle to the hypotenuse of the triangle.
Syntax: cos(Angle)
tan
The tangent of an angle is a trigonometric ratio of the length of the side opposite an angle to the length of the side adjacent to an angle in a right triangle.
Syntax: tan(Angle)
acos
The inverse cosine function, is the inverse function of the cosine function. It is the function that takes a ratio as an input and returns the angle whose cosine is equal to that ratio.
Syntax: acos(Number)

Other Formulas to find Hour angle

​Go Hour angle
ω=(ST3600-12)150.0175

Other formulas in Basics category

​Go Tilt factor for reflected radiation
rr=ρ(1-cos(β))2
​Go Tilt factor for diffused radiation
rd=1+cos(β)2
​Go Energy Conversion Efficiency of Solar Chimney
ηmax=9.81H1005Ta
​Go Declination angle
δ=23.45sin(0.9863(284+N))

How to Evaluate Hour Angle at Sunrise and Sunset?

Hour Angle at Sunrise and Sunset evaluator uses Hour angle = acos(-tan(Latitude Angle-Tilt Angle)*tan(Declination Angle)) to evaluate the Hour angle, The Hour Angle at Sunrise and Sunset formula is defined as a measure of the angular distance between the sun at the local solar time and the sun at solar noon. Hour angle is denoted by ω symbol.

How to evaluate Hour Angle at Sunrise and Sunset using this online evaluator? To use this online evaluator for Hour Angle at Sunrise and Sunset, enter Latitude Angle (Φ), Tilt Angle (β) & Declination Angle (δ) and hit the calculate button.

FAQs on Hour Angle at Sunrise and Sunset

What is the formula to find Hour Angle at Sunrise and Sunset?
The formula of Hour Angle at Sunrise and Sunset is expressed as Hour angle = acos(-tan(Latitude Angle-Tilt Angle)*tan(Declination Angle)). Here is an example- 2.09093 = acos(-tan(0.959931088596701-0.0959931088596701)*tan(0.40142572795862)).
How to calculate Hour Angle at Sunrise and Sunset?
With Latitude Angle (Φ), Tilt Angle (β) & Declination Angle (δ) we can find Hour Angle at Sunrise and Sunset using the formula - Hour angle = acos(-tan(Latitude Angle-Tilt Angle)*tan(Declination Angle)). This formula also uses CosineTangent, Inverse Cosine function(s).
What are the other ways to Calculate Hour angle?
Here are the different ways to Calculate Hour angle-
  • Hour angle=(Solar Time/3600-12)*15*0.0175OpenImg
Can the Hour Angle at Sunrise and Sunset be negative?
Yes, the Hour Angle at Sunrise and Sunset, measured in Angle can be negative.
Which unit is used to measure Hour Angle at Sunrise and Sunset?
Hour Angle at Sunrise and Sunset is usually measured using the Radian[rad] for Angle. Degree[rad], Minute[rad], Second[rad] are the few other units in which Hour Angle at Sunrise and Sunset can be measured.
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