n of the sun before. So the segment YX which is above the horizon will be less than a semicircle. For YXM was a semicircle and it has now been cut off by the Nike Roshe Run horizon AG. So Petr Mrazek Jersey part of it, YM, will be invisible when the sun has risen above the horizon, and the segment visible will be smallest when the sun is on the meridian; for the higher H is the lower the pole and Nike Air Max 2014 Damskie the centre of the circle will be.
In the shorter days after the autumn equinox there may be a rainbow at any time of the day, but in the longer days from the spring to the autumn Salomon Evasion MID Gore-Tex Kengät equinox there cannot be a rainbow about midday. The reason for this is that when the Mark Messier Jersey sun is north of the equator the visible arcs of its course are all greater than a semicircle, and go on increasing, while the invisible arc is small, but when the sun is south of the equator the visible arc is small and the invisible arc great, and the farther the sun moves south of the equator the Alex Galchenyuk Jersey greater is the invisible arc. Consequently, in the days near the summer solstice, the size of the visible arc is such that before the point H reaches the middle of that arc, that is its point of culmination, the point is well below the horizon; the reason for this being the great size of the visible arc, and the consequent distance of the point of culmination from the earth. But in the days near the winter solstice the visible arcs are small, and the contrary is necessarily the case: for the sun is on the meridian before the point H has risen far.
6
Mock suns, and rods too, are due to the causes we have described. A mock sun is caused by the reflection of sight to the sun. Rods are seen when sight reaches Naiset Nobis AUDRINA Bomber the sun under circumstances like those which we described, when there are clouds near the sun and sight is reflected from some liquid surface to the Nike Air Max 91 Męskie cloud. Here the clouds themselves are colourless when you look at them directly, but in the water they are full of rods. The only difference is that Nike Air Max 93 Herrar Skór in this latter case the colour of Moncler Clothing the cloud seems to reside in the water, but in the case of rods on the cloud itself. Rods appear when the composition of the cloud is uneven, dense in part and in part rare, and more and less watery in different parts. Then the sight is reflected to the sun: the mirrors are too small for the shape of the sun to appear, but, the bright white light of the sun, to which the sight is reflected, being seen on the uneven mirror, its colour appears partly red, partly green or yellow. It makes no difference whether sight passes through or is reflected from a medium of that kind; the colour is the same in both cases; if it is red in the first case it must Pteris Tall Czyścibut 5852 be the same in the other.
Rods then are occasioned by the unevenness of the mirror-as regards colour, not form. The mock sun, on the contrary, appears when the air is very uniform, and of the same density throughout. This is why it is white: the uniform character of the mirror gives the reflection in it a single colour, while the fact that the sight is reflected in a body and is thrown on the sun all together by the mist, Ugg Classic Short Paisley 5831 which islinks:
http://www13.plala.or.jp/white_roots/gwbbs/gwbbs.cgi
http://www.myip.cn/cgimage.lv
http://www.gymfan.com/board/step.cgi |
