My little guy and I were out for an early morning walk when he made the observation that the grass was wet but not the sidewalk. I told him that was "the dew" but he wanted to understand the topic more. So - here it is - the science "lesson" for the day on dew. Meet Dew:
When an object (such as a plant) gets SO cold - it cools the air around it. Then the water that is in the air around the object turns from water vapor (a gas) to water (the liquid!) and settles on the object.
video about dew
Want to calculate the dew point? That's the temperature an object needs to be in order for dew to form on it!
You get the temperature of the air in Celsius (call that "T"); and get the relative humidity (call that "RH") and do this fancy approximation calculation and it will spit out the dew point (call that Td which is the temperature that an object needs to be in order for dew to form on it!)
Td = T - ((100 - RH)/5.)
...are you like me and Fahrenheit just makes more sense....then these are the formulas you need to go back and forth:
| °C to °F | Divide by 5, then multiply by 9, then add 32 |
| °F to °C | Deduct 32, then multiply by 5, then divide by 9 |
...or even better yet - check out this fancy website - it takes all the math out!
Let's take a look at the things that affect dew point. You have arid (hot desert) vs moist climates. The more water in the air (moist climates) - the more likely dew will form.
Next up is wind! Wind can cause dew to not form because it moves around the water vapor in the air mixing the different layers and not allowing the dew to form.
So - if you have all this dew - can you collect if in places that need fresh water? It would be a renewable water source - right?!
Check this out - it's happening right now! https://www.youtube.com/watch?v=OnGR-j93JEw
and here! https://youtu.be/35yeVwigQcc
And it happened in ancient times. There is evidence that essentially rock piles were built to gather dew. In the 1930s a man built this:
This beast was to collect water - and it did! But only five gallons a day....the concept was simple. The stone on the inside remains cool and when warm air enters the structure, the air cools down allowing the water vapor to turn into water on the stones. Then the water drips down into a basin.
Here's another cool idea:
Yes! Water your plants with a stone pile!
Now - let's do some experimenting....
1. Build your own air well!
2. Take a can - fill it halfway with water etc
