Science & Technology


Over the weekend, I found myself riding a bus headed up north. Right in front of me was a kid I presumed was in preschool—seated next to her mom. As curious as kids go, I shifted my focus to their conversation when she asked her mom how fog is formed. I wasn’t quite sure if I wanted to hear how others understand the question or if, like the kid, I was also curious how adults would answer an unassuming question from a child. 

To cross it off the list, in case you have already forgotten, fog is a product of condensation. They are described as tiny water drops hovering in the air. When the air cools, water vapor turns back into liquid (condenses). If we go back to the basics of matter and its three states (solid, liquid, or gas) —we know that water vapor is gas. It’s invisible. So, when water vapor condenses, it could form dew, mist, frost, or fog (or clouds). On the ground, when water vapor condenses and interacts with some dust, they turn into fog. Fog is cool air mixing with warm moist air from the ground.

So how would you explain it to a kid?

Fog in Baguio Country club
Photo from Baguio.PH

The mom couldn’t have said any better when she explained that fog is a cloud on the ground. There is always water in the air, but sometimes, it’s made out of gas (water vapor), so we don’t see it sometimes. I like how she explained that fog usually forms after days of rain because, again, you would need a lot of water on the ground for the fog to form.  

She used the bottle of water her kid was holding to help her visualize it more. She explained that inside the bottle is cold water. Cold enough that soon after, the outside of the bottle becomes wet, making it seem like it’s sweating. She explained that the water does not pass through the bottle, but instead, because the cold bottle “played” with the warm air outside, the cold bottle collects water vapor into liquid drops—which makes the bottle wet. 

Fog in the Mountain Province
Photo from Sunstar by Jean Nicole Cortes

I was unsure if the kid could get the idea. But I think her explanation was good enough for her to know that fog and clouds are formed the same way. Through condensed tiny water droplets. How about you? How would you explain fog to a kid? 

Speaking of which, here’s a photo of Baguio fog at 3:37 in the morning when it reached 13 degrees yesterday.

Session Road covered with fog


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