佳木斯第五中学赵延荣.ppt

* * 佳木斯市第五中学 赵延荣 Blue light tints the sky blue ?? WHY is a clear, cloudless daytime sky blue? Don’t think this question is foolish. You’ll learn a lot about colour if you get the answer. ? A thick atmosphere (厚厚的大气层) goes around the earth. We are living at the bottom (底部) of all that air. There are dusts (灰尘), water drops and other small particles (颗粒) in the atmosphere . ? Sunlight passes through this thick air to reach the earth. It is made of lights of different colours. ? As sunlight travels through the atmosphere and meets particles, some of it scatters (散射). ? Are different lights scattered the same? No. Short wavelength (波长) light scatters more than long wavelength light. ? Light has different colours at different wavelengths. The wavelength of blue light is very short. It is about half the wavelength of red light, which is the longest. Blue light is scattered almost 10 times as strongly as red light. ? As blue light travels through the atmosphere it is scattered in all directions. So, blue everywhere in the sky! ? Text Curriculum focus: Scientific awareness: Getting to know why everything has its own colour. Language study: Learning words through context, and learning prepositional phrases. Pre-reading Have you noticed that everything has colour? Have you thought about why this happens? What is scattering? What do you know about light? While reading There are__________ in the atmosphere ? A. dusts , water drops and other small particles B. all kinds of lights. C. all kinds of color. D. blue sky. The wavelength of blue light is _______? A. very long B. very short In which direction is blue light scattered? A.scattered straight B. in all directions 4. We live where in all that air ? A. at the top B. at the bottom C. in the middle 5. __________________ goes around the earth. ? A. A thick atmosphere goes around the earth. C. Light goes around the earth. D. Nothing goes around the earth. Are different light