One of the most used devices to measure insolation is the Heliograph. Sunstroke is the number of hours the sun has shone in a certain place during a day. Thanks to this device, the sunlight that falls on an area can be recorded after two days. In this way, the duration of two days is known completely throughout the advance of the seasons.
In this article, we're going to tell you what a heliograph is, what its features are, and how to use it.
What is a Heliograph
It is a device used to measure the insolation that reaches a surface on a specific day. Heatstroke is also known for the amount of “effective sun” that reaches the surface. This device consists of a solar light recorder consisting of a solid glass ball about ten centimeters in diameter. This solid glass ball is used like a lens to concentrate all the sun's rays into a focus close to it. As the sun moves across the sky, this focus moves along a cardboard strip attached to a metal frame parallel to the video recorder.
This strip of cardboard is shaped like a semicircle and is located behind the solid glass ball. The concentration of the luminous and calorific focus traces a line through the more or less accentuated carbonization depending on the intensity of the solar rays. This is how insolation is measured.
The stripes show how the hours and half-hours of each day are marked. Throughout the day, the cardboard chars, creating a line that is more or less intense depending on the amount of light reaching it. If the sun is constantly flashing due to the presence of clouds, the light bulb does not act and therefore the burn line is interrupted. If the cloudiness disappears again, the carbonization of the cardboard resumes.
By adding the lengths of the lines that are burned throughout the day, you can see the total time of the sun's luminosity and the insolation of the corresponding day. It is known by the name of fraction of insolation to the relationship that exists between the actual insolation of a day and that which would have occurred if the sun had been continuously shining on the Heliograph ball. To learn more about meteorological instruments and their function, you can consult this link.
How to use the Heliograph
This device is placed on a masonry pillar at more or less a height of 1.3 meters from the ground. This is done so that there are no obstacles that could obscure it from the sun. A good place to place the Heliograph is one that allows visibility of the entire zodiac above the horizon at any time of year. This way, we can measure the amount of solar insolation from sunrise to sunset.
The heliograph must be positioned appropriately for the geographic latitude where we are. Remember that the amount of sunlight and solar irradiation vary depending on the latitude and altitude at which we are located. The sun's rays arrive at a more inclined angle as we approach the poles, being completely perpendicular at the equator. These devices generally They are manufactured for a small number of more typical latitudes that investigate insolation. A margin for final tuning is provided by means of a variable latitude device. This allows us to configure the Heliograph to work at any latitude.
What is set on the heliograph for latitude must also be set for longitude. The best way to do this is based on the equation of timeThis technique calculates with relative accuracy the time the sun passes over the dividing wall of a specific location. If the heliograph is used and is not properly adjusted, the marks or burns will not be parallel to the center line. This way, We run the risk of losing insolation data and not having exact measurements. To learn more about solar radiation, you can consult .
As the sun's altitude changes throughout the year, the focus of the Heliograph shifts accordingly. This means that the metal frame, which is provided with slots and guides, can be adjusted to find the most suitable position to facilitate calculations for each season.
The bands of the Heliograph are flat zonal stripes. These bands are narrow so that they can coincide with almost any area of the sphere.
How to interpret the data
If the sun has been shining continuously, it's fairly easy to count the actual hours of sunlight. Just measure the length of the charred line and look at the number of hours of direct sunlight. If the sun has been shining intermittently, you must proceed to count the total amount of sunlight in another way. You need a strip of paper or cardboard with a neatly cut edge and place it next to the heliograph strip. Use a sharp pencil to mark the lengths that have been burned. The image of the sun will not be mathematical. if not a little circle, each of the sections of the center of the semicircle must be taken as the origin and end.
To avoid errors when using these calculations, it's a good idea to use a special piece of paper or cardboard with a template that helps avoid additional calculations. There are some rules established by the INM for calculating sunlight hours. For example, if the path is cleanly burned, the furrow length will be reduced by a value equal to half the radius of the curvature at each end.
If the burns are circular, the mean length of the line should be equal to half the diameter of the burn. When the burn is no more than a narrow burn under a single spot, the entire length of the trace must be measured.
I hope that with this information you can learn more about the Heliograph.