Figure 1
This is a diagram of the seasons. Regardless of the time of day (i.e. the Earth's rotation on its axis), the North Pole will be dark, and the South Pole will be illuminated; see also arctic winter. In addition to the density of incident light, the dissipation of light in the atmosphere is greater when it falls at a shallow angle.

The angle at which sunlight strikes the earth, which varies by location and season, is an important factor in the amount of heat energy received at any location on the globe. Seasonal change in the angle of sunlight, caused by the tilt of the earth's axis, is the basic mechanism that results in warmer weather in summer than in winter (see Figure 1). (See also season.) This is a diagram of seasons that I made using Micrografx Designer software. ... Earth is the third planet from the Sun. ... The North Pole is the northernmost point on the Earth. ... Location of the South Pole in the Antarctic continent. ... The midnight sun at Nordkapp, Norway The midnight sun is a phenomenon, occurring in latitudes north of the arctic circle and south of the antarctic circle, where the sun is visible during at least 24 hours. ... A wave that loses amplitude is said to dissipate. ... Layers of Atmosphere (NOAA) Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... Prism splitting light Sunlight in the broad sense is the total spectrum of electromagnetic radiation given off by the Sun. ... The word axis has several meanings: In mathematics, axis can mean: A straight line around which a geometric figure can be rotated. ... Summer is a season, defined by convention in meteorology as the whole months of June, July, and August, in the Northern hemisphere, and the whole months of December, January, and February, in the Southern hemisphere. ... Winter is one of the four seasons of temperate zones. ... A season is one of the major divisions of the year, generally based on yearly periodic changes in weather. ...

When sunlight shines on the earth at a lower angle (sun closer to the horizon), the energy of the sunlight is spread over a larger area, and is therefore weaker than if the sun is higher overhead and the energy is concentrated on a smaller area. (See Figure 2.)

Figure 1 shows the angle of sunlight striking the earth in the Northern and Southern hemispheres when the earth's northern axis is tilted away from the sun, when it is winter in the north and summer in the south. Insert non-formatted text here The Northern Hemisphere is the half of a planets surface (or celestial sphere) that is north of the equator (the word hemisphere literally means half ball). On the Earth, the Northern Hemisphere contains most of the land and population. ... Southern Hemisphere The Southern Hemisphere is the half of a planets surface (or celestial sphere) that is south of the equator (the word hemisphere literally means half ball). On Earth it contains four continents (part of Africa, Oceania, most of South America, and Antarctica) and four oceans (South Atlantic...

Figure 2 depicts a sunbeam one mile wide falling on the ground from directly overhead, and another hitting the ground at a 30° angle. Trigonometry tells us that the sine of a 30° angle is 1/2, whereas the sine of a 90° angle is 1. Therefore, the sunbeam hitting the ground at a 30° angle spreads the same amount of light over twice as much area (if we imagine the sun shining from the south at noon, the north-south width doubles; the east-west width does not). Consequently, the density of incident light is only half as much. Wikibooks has more about this subject: Trigonometry Trigonometry (from the Greek trigonon = three angles and metro = measure) is a branch of mathematics dealing with angles, triangles and trigonometric functions such as sine, cosine and tangent. ... In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. ... Noon is the time exactly through the day, written 12:00 in the 24-hour clock and 12:00 noon in the 12-hour clock. ...

The sunbeam entering at the shallower angle must also travel twice as far through the Earth's atmosphere, which reflects some of the energy back into space. Saturns atmosphere is made up of hydorgen, helium and methane ...

Figure 2
One sunbeam one mile wide shines on the ground at a 90° angle, and another at a 30° angle. The one at a shallower angle covers twice as much area with the same amount of light.

See also

• Axial tilt
• Season