Changes in dna that sometimes do and sometimes don't have a harmful effect are called what?

A harmful one would be cutting down trees to make a new mall, This is the exact opposite of the one above, less food for plant or leave eating animals and less oxeygen

Explanation:

he movement of air through earth's or any planet's atmosphere is called wind, and the main cause of earth's winds is uneven heating by the sun. this uneven heating causes changes of atmospheric pressure, and winds blow from regions with high pressure to those with low pressure.

i hope this : )