Tham khảo tài liệu 'global warming part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Global Warming CO2 vs Sun 47 the other and back again covers two successive sunspot cycles and is therefore about 22 years. Fig. 23. Comparative sizes of the Sun Earth Moon and Earth-Moon distance. Sun diameter 1390000 km Earth diameter 12700 km Moon diameter 3474 km Earth-Moon distance 382500 km . Flares are the most violent eruptions in the solar system. Coronal mass ejections though less violent than flares involve a tremendous mass amount of matter . A single ejection can spew approximately 18 billion metric tons of matter into space. The Sun emits electromagnetic radiation in the form of visible light infrared radiation that we feel as heat ultraviolet rays microwaves X-rays gamma rays and so forth. This radiation can be thought of as waves of energy or as particle-like packets of energy the so-called photons. The energy of an individual photon is related to its frequency. All forms of electromagnetic radiation travel through space at the speed of light 299792 km s-1 . At this rate a photon emitted by the sun takes 8 minutes to reach the Earth that travels around the sun at an average distance of about 149600000 km. The amount of electromagnetic radiation from the sun that reaches the top of the Earth s atmosphere is known as the solar constant. This amount is about 1370 W m-2. Of this energy only about 40 reaches the Earth s surface. The atmosphere blocks some of the visible and infrared radiation almost all the ultraviolet rays and all the X-rays and gamma rays. Nearly all the radio energy reaches the Earth s surface. The Sun also emits particle radiation consisting mostly of protons and electrons comprising the solar wind. These particles come close to the Earth but the Earth s magnetic field Fig. 24 prevents them from reaching the surface. More intense ejections known as solar cosmic rays reach the Earth s atmosphere. Solar cosmic rays cannot reach the Earth s surface but they are extremely energetic they collide with atoms at the top of the atmosphere and
