Final answer:
The two main factors affecting snow crystal growth in the atmosphere are temperature and humidity.
Step-by-step explanation:
The two main factors affecting snow crystal growth in the atmosphere are temperature and humidity.
Temperature plays a significant role in determining the shape and size of snow crystals. As the temperature drops, the water vapor in the air freezes and forms ice crystals, which eventually grow into snowflakes through a process called deposition. The temperature range at which snow crystals can grow most readily is between -12 to -22 degrees Celsius.
Humidity, or the amount of water vapor present in the air, also affects snow crystal growth. Higher humidity provides more moisture for the ice crystals to grow and results in larger, more complex snowflakes. Conversely, low humidity can lead to smaller, simpler snow crystals.