## How do the seasons affect insolation – solar water heater electricity hair stand up

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explained was that the earth moves around the sun at an average speed of about 18.5 miles a second, and that on December 21 we are about 89.8 million miles from the sun, but 95.9 million miles from the sun on June 21. (This is because the sun isn’t always e85 gasoline in the exact center of our orbit.) Our childish logic might have told us that it should be the other way around: if we were closer in December, it should be warmer then — summer!

What we also may not have understood as very young children, but could grasp later on, was the fact that electricity in the 1920s the earth’s axis — about which we go round and round — is tilted 23.5 degrees from vertical. (What we may recall most vividly from those early astronomy lessons is that the earth’s axis points directly at the north star.) This axial tilt — not our distance from the sun — is what causes changes in the seasons (Figure 13).

As we spin once a day, 365.25 times, we move in a path around the sun one time. (One revolution accounts for a year of what we call electricity quizlet time, and the fact that each year has an extra quarter of a day explains why we need a leap year once every 4 years.) For some reason, as we get closer to the sun, our speed slows down slightly and then quickens again as we get further away. So

On June 21 — the summer solstice — we in the northern half of the rahal e gas card world are tilted most toward the sun so it hits us most directly. This is the day when we receive sunlight for the longest amount of time. On December 21, we are tilted farthest away from the sun. Then electricity notes for class 10 we get the fewest hours of sunshine and those rays we do get hit us at a pretty flat angle.

On March 21 and September 21 — the spring and fall equinoxes — there are equal amounts of sunlight and darkness. The Tropic of Cancer (23.5 degrees north), that weird parallel on the globe that seems out of spacing with the other latitude lines, marks the point where the sun is directly overhead at noon on June 21. The Tropic of Capricorn (23.5 degrees south bp gas prices chicago) describes the same path that most direct sunlight takes in the

Figure 14. The Tropic of Cancer indicates the northernmost gas pain relief point on earth where the sun can be directly overhead. This happens on June 21. On December 21 it is directly above the Tropic of Capricorn. This diagram shows the seasonal relationships between the sun and the earth. The normally recommended angle for a fixed solar collector is your latitude plus 10 to 15 degrees.

Figure 14. The Tropic of Cancer indicates the northernmost point on earth where the sun can be directly overhead. This j gastroenterology impact factor happens on June 21. On December 21 it is directly above the Tropic of Capricorn. This diagram shows the seasonal relationships between the sun and the earth. The normally recommended angle for a fixed solar collector is your latitude plus 10 to 15 degrees.

That’s how things look, theoretically at least, from outer space. But here on earth we’re looking at it from the opposite end, which gives us a very different perspective. What we earth beings see is this: On June 21 the sun appears higher in the sky at noon than it does at any other time of the year gaz 67. It is higher, in relation to the horizon, and this angle between the horizon and the sun is expressed as the sun’s altitude (Figure 15).

The sun is at its lowest altitude on December 21 — the winter solstice. On March and September 21 its position in the sky is midway between the other two extremes. We not only see less of the sun in December because natural electricity examples it is around for fewer hours, its intensity is diminished because of its low altitude. This is why we have winter (Figure 16).

Don’t be confused by insolation maps like the one gas definition chemistry in Figure 17. Here solar energy is being measured and described in Langleys rather than BTU’s. The Weather Service is simply using the language of the metric system instead of the old English system. A Langley is the amount of heat it takes to heat one gram of water one degree centigrade. To convert Langleys per day to BTU’s just multiply the number of Langleys by 3.69 (Table 7).

Before you make a commitment to a solar heating system of any kind you electricity in costa rica should study how much sunlight falls on your area at all times of the year. Solar insolation maps that are even more accurate than U.S. Weather Service maps can be found in a book called World Distribution of Solar Radiation, by Smith, Duffie and Löf. For a copy of this title write to the University of Wisconsin, Engineering Experiment Station, 1500 Johnson Drive, Madison, Wisconsin 53706, and send them a check for \$6.00. You may electricity voltage in india also get more specific climatic information from your nearest Weather Service office. And The Old Farmer’s Almanac, although not always precise, is another good source of general weather data (Figure 17).