Now scan the text again to find the answers to these questions

Look at the definitions of the following words and try to guess what they mean.

a) Wavelength – the distance between one peak of a wave of light, heat, or other energy, and the next corresponding peak.

b) Absorb – retain wholly, without reflection or transmission.

c) Observer – the one who watches attentively.

d) Particle – a very small piece or part.

e) Matter – something that has mass and exists as a solid, liquid, or gas

e) Light – electromagnetic radiation of any wavelength.

3. Read the text:

WHY IS THE OCEAN BLUE?

Why is the ocean blue? There are several theories:

o Blue wavelengths are absorbed the least by the deep ocean water and are scattered and reflected back to the observer’s eye.

o Particles in the water may help to reflect blue light.

o The ocean reflects the blue sky.

Most of the time the ocean appears to be blue because this is the color our eyes see. But the ocean can be many other colors depending upon particles in the water, the depth of the water, and the amount of skylight.

The colors we see depend upon the reflection of the visible wavelengths of light to our eyes. Wavelengths of light pass through matter differently depending on the material’s composition. Blue wavelengths are transmitted to greater depths of the ocean, while red wavelengths are absorbed quickly. Water molecules scatter blue wavelengths by absorbing the light waves, and then rapidly reemitting the light waves in different directions. That is why there are mostly blue wavelengths that are reflected back to our eyes.

Sometimes oceans look green. This may be because there is an abundance of plant life or sediment from rivers that flow into the ocean. The blue light is absorbed more and the yellow pigments from plants mix with the blue light waves to produce the color green.

Sometimes parts of the oceans will look milky brown after a storm passes. This is because winds and currents associated with the storm churn up sand and sediment from the rivers that lead into the oceans.

The ocean may also reflect the blue sky. However this is prominent only at relatively low angles and when the water is smooth.

4. Answer these questions on the text:

1. What color of the ocean is not mentioned in the text?

a) Milky brown

b) Green

c) Purple

2. Some parts of the ocean look milky brown

a) When it snows a lot.

b) After a storm.

c) When the sun shines brightly.

3. The ocean reflects the sun

a) When the water is smooth.

b) When there is no fog.

c) When the sun shines at right angle.

1. What are the three theories explaining why the ocean seems blue? Which one do you think is true? Why?

2. What do the colors of the ocean we see depend on?

3. How can you explain the fact that sometimes the ocean looks green?

4. Wavelengths of what color are absorbed quickly?

5. Why are blue wavelengths reflected to our eyes?

Дата добавления: 2015-05-24