It was a nice morning at the Science Cave. Professor Bradley Brachiosaurus was enjoying the sunshine while sitting on a bench beside the cave entrance. He was reading the latest issue of “DinoWorld Science” as he drank his coffee.
Soon he heard two young dinos coming up the path.

“Good morning, Angie Ankylosaurus. How are you?”
He asked. “I’m fine, Professor.” Angie answered.
“And who is your friend here?” The professor inquired.

“This is my friend Ophelia Othnielia (Oth-knee-lee ah). Her mother and my mother are cousins. I think that makes us second cousins or something. Anyway, her family will be staying here for a few months while her dad works on a project in Swampville. We’re best friends!” Angie hugged Ophelia.

“I’m glad to meet you, Ophelia! How do you like it here? Are you having fun?” Professor Bradley took a drink from his huge coffee mug.

“I like it fine, but I miss the mountains and the cool nights. I guess it is O.K. to see some more places.” Ophelia smiled. “My mom doesn’t like it a whole lot, though. She is having a terrible time making her tree stump stew. She says that she just can’t seem to cook things right.”

Professor Bradley exclaimed, “Oh ho! That is to be expected – coming from the high country.”

“Why do you say that, Professor?” Angie and Ophelia asked.

“Why, the air is heavier here near the seashore, and lighter in the mountains, of course.”

Angie and Ophelia looked puzzled.

“Are you joking with us, Professor Bradley? I don’t think air weighs anything!” Angie looked curious.

“And I can hold two handfuls of air, and I don’t feel anything at all.” Chimed in Ophelia.

“We all take it for granted, so we don’t even think about it, but it does affect your mom’s cooking. Here’s how.”And Professor Bradley proceeded to explain.

“What happens in the mountains is that there is less air pressure so the water in your mother’s cooking boils at a lower temperature than down here in Dinoville, because we are closer to the seashore. Your mom has learned to cook her food longer so that it gets done properly. Down here, water boils at a higher temperature, and food gets cooked faster. She is probably over cooking your meals. It will take a little time before she gets the cooking rate adjusted. You know, when you heat water, the water particles start to bounce and move around."

“Are you sure, Professor?” Asked Angie. “I don’t think I have ever seen that.”

“You sure have, Angie. Watch the little bubbles in the water next time your mom boils procompsognathus (pro-comp-sog-nath-us) eggs for breakfast. At high altitudes, the weight of air, or air pressure, is less so some particles jump into the air. This is when the particles turn into steam and evaporate. At the altitude of Dinoville, it takes a higher temperature, so it takes longer for the water to boil.”

“I’m sure you are right, Professor Bradley, but I still don’t see how air could weigh anything.”

“The air pressure doesn’t just press down, Angie. It isn’t the same as feeling the weight of a rock in your hand. Air presses in on all sides of your hand. If you stick your hand down into a bucket of water, you can feel its pressure on all sides of your hand. Air is the same, only there isn’t as much pressure.” Professor Bradley thought for a moment and then said,“I think I know how to demonstrate this for you. Would you like to see a small experiment? Angie and Ophelia, you young dinos wait here while I get some materials out of my laboratory.”

Professor Brachiosaurus went into the Science Cave and returned with a four-inch square of paper and a glass full of water.

“Here,” He said, placing the glass of water on the table,“The water in the glass has air pressure on it. Ophelia, place the square of paper on top of the glass. See how the paper is starting to get wet because the glass is full to the top? Keep one hand holding the paper on top of the glass. If you hurry, before the paper gets too wet, you can pick up the glass of water with the other hand and turn it over! Ophelia, take your hand off the paper.”

“Wow!” Angie was excited. “Look! The water is staying in the glass!”

“Yes, Angie. The water will be held in the glass until the paper has soaked through.” Said Professor Bradley.

“Ophelia, I can’t wait to show the others! Can you?” Asked Angie.

“Let’s go!” Ophelia put the glass back down on the table.

“Before you leave, girls, remember 2 things:

The water is held in the glass by the air pressure against the paper. Remember to do this outside, over a kitchen sink, or in the bathtub.

“We don’t want to get you in trouble with your moms.”Professor Bradley grinned.

Angie and Ophelia said, “Thank you, Professor Bradley!” and they hurried home.

The End