💎 WHAT IS THE HELIOGRAPH AND WHAT IS IT USED FOR ?

What is the Heliograph ?

It is a device used to measure the level of insolation that reaches a surface on a given day. Sunstroke is known as the amount of «effective sun» that reaches a surface.

What is the Heliograph Used for ?

The Heliograph is a measuring instrument used to determine the solar light intensity, as well as the duration of the daily insolation on a certain place. In addition, it is used to determine the relative position of the sun with respect to the Earth at all times, so it provides highly useful information for areas as diverse as meteorology, agriculture and even tourism.

Types of Heliographs

The most widely used heliograph is the so-called Campbell-Stokes heliograph. Other heliographs are the Jordan heliograph and the Marvin heliograph.

There are different kinds of heliographs. While some include clockwork mechanisms for their operation, others use the rotation of the planet Earth to calculate time.

Parts of a Heliograph

The traditional heliograph is made up of a crystal ball, a band and a focus of the sphere. The crystal ball that is part of the traditional heliograph is massive, about 96 millimeters in diameter.

How Does the Heliograph Work ?

The function of the crystal ball is to focus the sunlight on a band that, when burned, produces a trace. So the ball operates like a lens. That band is located at a constant distance from the focus of the sphere.

The time of insolation is determined taking into account the length of the trace charred by the solar rays, as long as the sun has shone without pauses. When the solar brightness is not continuous, the extensions of the different segments of traces left are added, which appear intermittently.

Depending on the time or season of the year, three different kinds of bands are usually used. Each type of band is briefly described below, taking the planet’s northern hemisphere as a reference:

Straight belts

They are installed attached to the slots in the center of the bracket. They are commonly used from the beginning of March to the middle of April, and from the beginning of September to the middle of October. Since these bands are referred to as the so-called «equinoxes», they are known by the name of equinoctial bands.

Short curved bands

They are installed in the slots at the top. They are commonly used between the month of October and the end of February.

Long curved bands

They are installed in the slots at the bottom. They are commonly used between the months of April and August.

What does the Heliograph Measure ? Unit of Measurement

The heliograph measures time, the duration of sunlight or insolation as a physical magnitude. The unit that is usually used is the hour as we know it. For climatological purposes, expressions such as: «hours of effective sunshine in the day», «hours of sunshine a day», or «hours of daily sunshine» are often used.