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What Is a Sunshine Recorder?

Direct sunlight activates the Campbell-Stokes sunshine recorder.
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  • Written By: Dee S.
  • Edited By: C. Wilborn
  • Last Modified Date: 26 September 2014
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One way that the duration of "bright sunshine" is measured is through a Campbell-Stokes sunshine recorder. It is comprised of a glass canister or sphere that directs sunlight onto a card that is treated with a special chemical. The sunlight burns or chars a mark onto the card. This marking, called a trace, is measured and converted into a duration of time. The term "bright sunshine" means that the Campbell-Stokes sunshine recorder is unable to work properly when the sun is going down or rising for the day, only when it is able to provide direct rays of sunlight.

With the Campbell-Stokes sunshine recorder, the card is changed one time each day. It is relatively accurate and provides a total duration of sunshine to the nearest tenth of an hour every day of the year. The sun changes elevation several times throughout the year, so there are three different cards that can be used. The cards are associated with the different seasons and are created to fit with the elevation of the sun.

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Occasionally, the readings that are created with the sunshine recorder are hard to interpret; however, it has been used for years. Sometimes the traces or marks on the cards burn too deeply, making them a challenge to read. Interestingly, there are electronic versions of the Campbell-Stokes sunshine recorder. The readings of these electronic models are usually much simpler to follow, making them a new favorite. The readings are converted to the Campbell-Stokes valuation, making the data easy to compare.

A new version of sunshine recorder is electronic solarimeter. It can read the intensity of solar radiation and expresses its data in watts per square meter. Solar radiation can be in one of two forms: direct or diffuse. If it is direct radiation, the radiation reaches the solarimeter directly from the sun. If it is diffuse radiation, it reaches the solarimeter after it is scattered by dust, particles in the atmosphere, and gas molecules. The readings are helpful for those interested in agriculture and changes in climate.

Scientists are always researching new ways to measure sunlight. The older sunshine recorder is quickly being replaced with newer, more sensitive devices, like the solarimeter. As the sunshine recorder becomes obsolete, some collectors and individuals interested in tracking the sun at home have begun their quest to purchase their own recorders. Prices vary depending on the quality and size of the device.

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Georgesplane
Post 4

@cougars- Diffuse and direct solar radiation are very important to solar energy. Solar thermal systems used for water and space heating can effectively use diffused solar radiation by absorbing the heat from said radiation. Solar thermal collectors used to generate electricity, on the other hand, cannot use diffuse radiation to generate electricity since they concentrate beams of direct solar radiation to heat water and run a turbine or stirling engine.

Photovoltaic systems, on the other hand, can generate electricity with diffuse solar radiation, although the amount of energy produced falls off. This allows PV systems to effectively generate electricity in partly overcast conditions. I hope this helps explain types of solar radiation, and how they affect solar energy.

Glasshouse
Post 3

@Cougars- Sunshine recorders, wind meters, and other climate devices are actually quite expensive. A Campbell-Stokes Sunshine Recorder can run upwards of $3000 and is quite bulky to carry. Much more equipment than would be needed for a fun day in the park. I would suggest printing up some solar radiation maps for your city or state, and buying a small solar panel kit.

I used to have one when I was a teenager that allowed me to make a small solar array that powered a fan. I installed it on the side of my tree house to give me a little ventilation. You can find a decent kit for less than $100 and it might inspire your children to learn more about solar energy. My parents bought me all types of science kits and toys as a child, and now I am an environmental scientist studying renewable energy and resource management.

cougars
Post 2

I have heard of instruments used to measure wind speeds, but I did not know there were specialized instruments to measure solar radiation. Does it matter if the solar radiation is direct or diffused when it comes to solar energy? How much solar radiation is necessary to install solar panels? Where can I find a sunshine recorder? I would be interested in taking my kids to the park to take sunshine readings and teach them about the solar energy.

GenevaMech
Post 1

Solar readings are also important for those planning to install residential, commercial, or utility scale solar arrays. Solar radiation intensity (basis of solar insolation) is measured in Watts per square meter. A survey is conducted that uses sunshine recorders to determine the solar insolation of an area. Solar insolation is essentially the amount of energy in a given area per day.

The standard measure for solar insolation is given as kilowatt-hour, per square meter, per day (kWh/m^2/day). The insolation tells solar technicians what collector area would be necessary to achieve a certain power output. There are a number of charts that can be used for smaller installations that give the average insolation over a period of years, but utility scale installations will use their own surveys conducted over a certain period.

An average annual insolation of 5.5 would be considered very high, only being found in Phoenix, Los Angeles, and Honolulu within the United States. On the other hand, a solar insolation of 5.5 for the summer months would be considered low. In the lower 48 states, solar insolation levels range from 0.9 in the winter to 7.7 in the summer.

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