【明報專訊】The Smarties get into a hot air balloon for a better view of the rainbow.

From high above the ground, they also get a bird's-eye view of the city!

Shape of a rainbow

Did you know a rainbow's shape is actually a full circle? Since we usually look at a rainbow from the ground, we see only a half of it.

Why ''rainbow''?

This natural phenomenon is called a rainbow because its arc looks like a bow for shooting arrows and it appears on rainy days. Red is seen on the outer edge of the arc, and violet, on the inner edge.

Roy G Biv

Do you know what Roy G Biv is? Roy G Biv stands for ''red, orange, yellow, green, blue, indigo and violet''! They are the seven colours of a rainbow. A rainbow commonly occurs when beams of sunlight strike raindrops in front of a viewer at an angle of 42 degrees.

■Mission 1

Do you know what double rainbows and moonbows are? Those are types of rainbows which are rarer. Fill in the blanks with the words provided to learn more about them!

outer / inner / opposite / through / outside / near

When sunlight is reflected twice in water droplets, a secondary rainbow appears 1. _________ the primary arc. This secondary reflection is much fainter. The order of the secondary rainbow's colours is the 2. _________ of that of the primary rainbow's. Violet is on its 3. _________ edge, and red, on its 4. _________ edge. One may also see rainbow colours 5. _________ the moon at night. That is called a moonbow or lunar rainbow. It happens when moonlight reflects 6. _________ raindrops in the atmosphere. This phenomenon is rare because moonlight is much dimmer than sunlight.

■Mission 2

Observe the colour pattern of the structure below. Can you tell which of the five pictures on the right Bill can see through his monocular?

(see the picture)

■Mission 3

The hot air balloon is flying over another structure in the shape of a regular triangular pyramid (正三角錐體) which rotates in all directions. Once again, Bill is looking at it from above. Which one of the five figures is not a possible bird's eye view of the same pyramid?

(see the picture)

(answers on next text)

“ Eason: Why am I not allowed to join? ”

■English highway﹕-nouns and articles

beam

Beam means a ray or stream of light or other radiation.

e.g. The car's headlights were on full beam.

■Key words

natural phenomenon 自然現象

double rainbow 雙彩虹

moonbow 月虹

fog bow 霧虹

■Glossary

bird's-eye view (n phr) 鳥瞰

arc (n) 弧形

violet (n) 紫羅蘭色

indigo (n) 靛藍色

faint (adj) 微弱的

lunar (adj) 月亮的

atmosphere (n) 大氣層

monocular (n) 單筒望遠鏡