Small asteroids tend to burn up in the atmosphere.
Moderately sized asteroid may cause an impact crater and impact local conditions.
A massive asteroid can cause:
(1) a massive crater or above ground explosion
(2) blast wave
(3) thermal pulse wave
(3a) marked rise in temperature
(3b) widespread fire
(4) ejection of debris into the atmosphere
(4a) large objects re-enter as rock bombs
(4b) small dust may enter the stratosphere, causing a fall in global temperatures with prolonged winter or other climate change
(4c) acid rain
(5) triggering of an earthquake, volcano, landslide and/or tsunami
(6) vaporization of any metal or mineral in the asteroid which can be inhaled or contaminate the soik
