Where is insolation the greatest year round

Solar radiation , often called the solar resource or just sunlight, is a general term for the electromagnetic radiation emitted by the sun.

Solar radiation can be captured and turned into useful forms of energy, such as heat and electricity, using a variety of technologies. However, the technical feasibility and economical operation of these technologies at a specific location depends on the available solar resource.

Every location on Earth receives sunlight at least part of the year. The amount of solar radiation that reaches any one spot on the Earth's surface varies according to:. When the sun's rays are vertical, the Earth's surface gets all the energy possible. The more slanted the sun's rays are, the longer they travel through the atmosphere, becoming more scattered and diffuse. Because the Earth is round, the frigid polar regions never get a high sun, and because of the tilted axis of rotation, these areas receive no sun at all during part of the year.

The Earth revolves around the sun in an elliptical orbit and is closer to the sun during part of the year. When the sun is nearer the Earth, the Earth's surface receives a little more solar energy. The Earth is nearer the sun when it is summer in the southern hemisphere and winter in the northern hemisphere.

However, the presence of vast oceans moderates the hotter summers and colder winters one would expect to see in the southern hemisphere as a result of this difference.

The At the June solstice, average daily insolation will be greatest, since the Sun is in the sky longer and reaches higher elevations. At the December solstice, daily insolation will be least, with a shorter daily path and lower elevations. At the equinox, the insolation will be intermediate. At the North Pole, the Sun moves in a circle in the sky at an elevation that changes with the seasons.

At the Equator, the Sun is always in the sky for 12 hours, but its noon angle varies through the year. At the Tropic of Capricorn , the Sun is in the sky longest and reaches its highest elevations at the December solstice. Based on this analysis, daily insolation will vary strongly with season at most latitudes. As shown in Figure 2. Insolation drops to zero at the North Pole at the September equinox, when the Sun's circular path sinks below the horizon, and does not increase again until the March equinox.

At the solstice, insolation is lower because the Sun's path is lower in the sky Figure 2. How does latitude affect annual insolation—the rate of insolation averaged over an entire year? Let's look first at the real case of a tilted axis. We can see that annual insolation varies smoothly from the Equator to the pole and is greater at lower latitudes. But high latitudes still receive a considerable flow of solar energy—the annual insolation value at the pole is about 40 percent of the value at the equator.

Now let's look at what would happen if the Earth's axis was not tilted. With the axis perpendicular to the plane of the ecliptic, there are no seasons. On December the 21 st Mr Gs birthday! Hence the North Pole receives no insolation at this time and the Tropic of Capricorn its maximum amount.

The Northern and Southern hemispheres are in spring and autumn respectively. On June the 21 st , the Earth has continued its journey so that the maximum overhead sun is over the Tropic of Cancer This accounts for the seasonality of Insolation, but what about the total amount received by different attitudes? The total amount of insolation received by the latitudes of the Earth does not vary a great deal, but the curvature of the Earth ahs a vital role to play in determining how much Insolation is received by different places.