Pamela Crosby, age 8, of Newport News, Virginia, for her question:

Is it ever too cold to snow?

As a rule, the snow flakes come fluttering down when the winter weather is not very cold and frosty. After the snowfall, we may get a spell of shuddering cold and the sky becomes blight and clear. We can be pretty sure that no snow will fall from such a frosty blue sky. But the weather is full of surprises and even the weatherman sometimes get fooled. The experts say it never really gets too cold to snow    but snow is less likely to fall when the air is very clear and extra frosty.

This is because the air must have moisture to build lacy snowflakes. It so happens that warm air drinks up more moisture. Cold air is drier because it has to give up some of its moisture. So extra chilly air has less moisture for making snowflakes. This is why it is less likely to snow in shuddering cold weather. However, there is some moisture, even in the driest air. This is why weather can fool us with a few small snowflakes, even when the air is colder than cold.