At the point of incidence where the ray strikes the mirror, a line can be drawn perpendicular to the surface of the mirror. This line is known as a normal line (labeled N in the diagram). The normal line divides the angle between the incident ray and the reflected ray into two equal angles. The angle between the incident ray and the normal is known as the angle of incidence. The angle between the reflected ray and the normal is known as the angle of reflection.
Even if the water were to be cooled from the bottom, the coldest water would float to the top and when the whole pond became 0Â°C the ice would float to the top as it formed. In some cases where rocks are below the freezing point (exposed to the air part of the time, ice can form and stick to the rocks under water.
Ocean water freezes at a lower temperature than freshwater. At least 15 percent of the ocean is covered by sea ice some part of the year. Ocean water freezes just like freshwater, but at lower temperatures. Fresh water freezes at 32 degrees Fahrenheit but seawater freezes at about 28.4 degrees Fahrenheit, because of the salt in it. When seawater freezes, however, the ice contains very little salt because only the water part freezes. It can be melted down to use as drinking water.