4 . You have probably eaten a hot dog, but have you ever spotted a sundog? This isn’t your pet dog napping in the sun!
A sundog is a weather event that causes two bright bursts of rainbow colored light to appear on either side of the sun. You would see them around 3 o’clock and 9 o’clock. Sundogs can be very beautiful, with a red glow closest to the sun and a white in the center. The scientific name for sundogs is parhelia, which comes from a Greek word meaning “beside the sun”.
Conditions need to be just right for sundogs to appear. Sunlight passes through high clouds that spread out like feathers in front of the sun. These clouds contain flat, six-sided ice crystals (晶体). If the crystal drifts toward the ground, with the larger face facing the Earth, light is refracted (折射). These crystals then separate the light, forming a sundog.
Sundogs can be seen during any season but are most often seen during the winter months when the sun is lower in the sky. You are also more likely to see them early or late in the day, when the sun is near the horizon. Sundogs have been spotted around the world, across North America, Europe, and Asia, at the South Pole and in the far north. Scientists have even predicted what sundogs might look like on other planets.
Throughout history, sundogs have been used to predict weather because they indicate snow or rain on its way. Some people believed that sundogs were a sign of good luck, while others saw them as a warning from God. Shakespeare described sundogs in poems as frightening.
Ready to try out your weather detective skills? First, use your hand to block the center of the sun to protect your eyes. Search for clouds in a winter sky and a circle or burst of light around the sun. Be sure to show off your sundog smarts to your friends and family — you’ll be their top dog!
1. What can be inferred about a sundog from the passage?
| A．It leads the sun to produce crystals. | B．It forms under strict circumstances. |
| C．It causes the appearance of rainbow. | D．It separates the sun from high clouds. |
2. Which of the following conditions is most suitable for observing a sundog?
| A．One summer midday in China. | B．One late winter night in America. |
| C．One winter morning in Europe. | D．One summer morning in the Arctic. |
3. Why is Shakespeare mentioned in the 5th paragraph?
| A．To convince readers of the beauty of sundogs. |
| B．To illustrate the wide range of topics of his poems. |
| C．To help readers understand the function of sundogs. |
| D．To show impressions of sundogs vary among viewers. |
4. What tone does the writer use in the last paragraph?
| A．Confident. | B．Encouraging. | C．Worried. | D．Fearful. |
