Question 1: Explain why a mirage disappears when the observer gets near

Mirage is an optical illusion in which “water” appears close to the ground surface. The illusion is caused by an interplay of refracted and reflected light from warm and cold air pockets near the surface. The warm and cold airs have different density and therefore different refraction index, which result in different angles of reflection. The warm air is continually rising and mixing with cold air, to create a continually changing reflection that appears like water.

Question 2: What particles (cloud droplets, rain drops, or ice crystals) are associated with Rainbow

Rainbow occurs when light falls on rain droplets and is refracted, reflected and dispersed. The light comes from behind the observer at an angle of 40 to 42 degrees.

Halo

A halo forms when ice crystals are refracted by large droplets of ice crystals that bend the light at either 22 degrees for 22-degree halos, or 46 degrees for 46-degree halos. The halo is a circular formation.

Corona

Corona forms when light is diffracted by either tiny ice crystals, or small cloud droplets creating a larger corona.   

Glory

A glory is a small circular rainbow that resembles a halo and that surrounds an observer. It is caused by reflection of light from the sun or moon as it passes through a dense mass of cloud droplets below it. The angle of reflection is between 5 and 20 degrees.

Sun Dog

Sun dog is a bright glowing red light that appears as a ball of light with striking rays at horizontal and vertical direction. They form when light is refracted from ice crystals high in the atmosphere.  

Question 3: White sunlight is separated into the rainbow colors. Match features numbered 1 through 5 with the terms

Number 1 is Incident ray

Number 2 is refracted light

Number 3 is internal reflection

Number 4 is Violet light

Number 5 is Red light

Question 4: The large screen of a movie theater is made of small glassy particles oriented at slightly different angles rather than one very smooth surface. Based on what you know about how light is reflected from various surfaces, why do you think this type of screen is used?

A movie theater screen is created this way in order to make images clearer and brighter by reflecting the excess source light called “hot spot” back to the light source.

Question 5: Explain why the refraction of sunlight causes the length of daylight to be longer than if the earth had no atmosphere.

The sunlight lingers on after sunset because the light is refracted and reflected by air particles to different directions, including towards the horizon in the dark zone (night), which makes the daylight linger on longer.  This phenomenon continues until the sun reaches six degrees or 30 minutes below the horizon. It occurs when the sun is from zero and up to six degrees below the horizon.

Question 6: Explain why a person in Lincoln, Nebraska (41 degrees latitude), will never see a rainbow at noon on June 21.

The rainbow can only be seen at an incident angle of 40 to 42 degrees. On June 21 the sun is 41 behind the observer and therefore reflection of light through the water droplets is at beyond the 42 degrees required for a rainbow to occur.  

Question 7: Name each of the optical phenomena shown in the accompanying photos.

(a) sun dog

(b) solar glory and Brocken specter

(c) 22 degree sun halo

(d) low arch rainbow