What is a tangent arc in relation to a halo??
What will be the ideal response?
ANSWER: Occasionally, a bright arc of light may be seen at the top of a 22° halo. Since the arc is tangent to the halo, it is called a tangent arc. Apparently, the arc forms as large six-sided (hexagonal), pencil-shaped ice crystals fall with their long axes horizontal to the ground. Refraction of sunlight through the ice crystals produces the bright arc of light. When the Sun is on the horizon, the arc that forms at the top of the halo is called an upper tangent arc. When the Sun is above the horizon, a lower tangent arc may form on the lower part of the halo beneath the Sun. The shape of the arcs changes greatly with the position of the Sun.
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When a species disappears from the earth, it is said to be biologically extinct.
Answer the following statement true (T) or false (F)
A community of different species interacting with one another and the physical and chemical factors of their nonliving environment is called a(n)
a. Species b. Ecosystem c. Population d. Lithosphere e. Community
What is the nature of the water table?
A. Infiltrating water generally passes through the water table to become groundwater. B. Below the water table, water fills pore spaces and can flow. C. It is the boundary between the saturated zone and unsaturated zone. D. All of these choices are correct.
Manipulative experiments
A. are most often conducted in a laboratory. B. are not possible. C. do not allow the scientist to control variables. D. are not useful to ecologists because they depend on the natural environment.