Air molecules and dust particles in the atmosphere will scatter sunlight. From a consideration of the position of the sun, estimate the direction of incidence of the sun's rays on the atmosphere. In what direction will an observer on the earth's surface need to look if he is to observe scattered light which is plane polarised? Confirm your prediction using a sheet of Polaroid to analyse 'sky' light. A cloudy sky will not prevent observations. With reference to a diagram, describe where the sky showed the maximum polarisation by scattering and describe the position of the plane of polarisation.
This was one of my favorite physics labs...it got us outdoors in the spring.
https://www.polarization.com/sky/sky.html
To estimate the direction of incidence of the sun's rays on the atmosphere, you need to consider the position of the sun. The sun is highest in the sky at noon and lower in the morning and evening. Therefore, if you stand on the Earth's surface, the direction in which you need to look to observe scattered light which is plane polarized will be perpendicular to the sun's position.
To confirm this prediction using a sheet of Polaroid to analyze 'sky' light, follow these steps:
1. Take a sheet of Polaroid and hold it in front of your eyes.
2. Look towards the sky in the direction perpendicular to the sun's position.
3. Rotate the Polaroid sheet while looking at the sky.
4. Observe changes in the intensity of light passing through the Polaroid sheet as you rotate it.
By following these steps, you will notice that there is a particular angle of rotation at which the intensity of polarized light passing through the Polaroid sheet is maximized. This angle corresponds to the direction in which scattered light in the sky is plane polarized.
Referring to the diagram, the sky will show maximum polarization by scattering in directions perpendicular to the sun's position. If the sun is located at a higher position in the sky (e.g., noon), the maximum polarization will be observed in the horizontal plane. If the sun is lower (e.g., morning or evening), the maximum polarization will be observed in a tilted plane.
The position of the plane of polarization will be perpendicular to the direction from the observer to the sun. When observing with the Polaroid sheet, find the orientation at which the intensity of light passing through is maximum, and that will correspond to the position of the plane of polarization.
It is worth noting that even a cloudy sky will not prevent you from making these observations, as long as there is scattered light present.