Image source: NOAAĪs the earth continues its orbit around the sun, it reaches a point where its tilt is sideways to the sun. These extra hours of sunlight gives the sun more time to heat the earth and this is the main reason for summer to be the hottest season.
In addition, because the sun is in the sky for more hours, the summer solstice is also the longest day in the year. On this day, which can be referred as the first day of summer, the sun’s path is higher in the sky than it is on any other day in the year. Around June 21st, the northern hemisphere is tilted the most towards the sun and is called as the Summer Solstice. As a consequence, the sun’s path is higher in the sky, causing the northern hemisphere to receive more light and heat. The earth rotates about its own axis, titled at an angle of 23.5° degrees to its orbital plane and at the same time, travels around the sun in a huge circular path through space.ĭuring summer, the North Pole is tilted towards the sun. Image credit: Clay Atchison, Now, this brings us to the next question – why is the sun higher in the sky in summer? The answer lies in the earth’s rotation about its tilted axis and it orbit around the sun.
Higher it is in the sky, the more direct and intense the sunlight would be. What it implies is that, direct 90° degree angle provides more intense light than the inclined one. You will now observe that the size of the lit area has increased, but the intensity or brightness of it has reduced. Now, slowly reduce the angle to make it less direct. In a darkened room, switch on the flash light on a surface, at a direct 90° degree angle. To understand it more clearly, let’s do a simple demonstration using a flash light.
This makes the days longer and it makes the summer sun more intense. The summers are hotter because, the sun’s path is higher in the sky. Also, when it is summer in the northern hemisphere, it is winter in the southern hemisphere. We all know that summers are hotter and winters are colder. Let’s begin by trying to understand the earth’s rotation about its axis, its orbit around the sun and the four seasons.
But how to find the sun motion relative to a site? Meaning, we need to chart the sun’s position throughout the year. Beehives, chickens, fish ponds and livestock, all appreciate sunshine in winter and shade in summer.įor a given site, if we can create a chart that shows the areas of year round shade and year round sunshine, one can plan and design the various elements for optimal functioning. Even animals can derive benefits from thoughtful solar designs, as they too like to have winter warmth and summer shade.
Houses outside the tropics need to be designed/oriented to make more winter sunlight enter the living spaces, while for those in the tropics, they should be designed/oriented to have more shade and cooler air entering the living spaces. Other elements of a permaculture design like solar panels are also needed to be placed thoughtfully to obtain maximum exposure to the sun to harvest as much energy as possible. A good appreciation of the earth’s rotation about its axis, its revolution around the sun and the consequences of these motions on the sun’s position and availability at a given location on the earth’s surface, is essential for maximizing plant productivity, harnessing maximum energy, minimizing energy usage and maintaining a comfortable indoor environment for humans and animals alike.įor proper functioning and productivity gardens, greenhouses and orchards should be placed at specific locations based on the adequate availability of sunshine for the parts of the year in which the plants are growing or fruiting. Understanding the sun’s motion relative to a site is an important aspect of a good permaculture design, as various elements like plants, animals and solar devices depend on sun for their functionality.