The Sky Traveller with a secret memory
Today, Mia looked out of the window and saw clouds racing across the Arctic sky. She thought about how Nina once explained how these clouds are formed from the water vapor.
“Mika,” she said to her little Arctic fox, “If clouds are formed from water vapor, do you know where this water came from?”
“From the sea,” Mika said. “Or maybe from a lake.”
“Or from someone’s hot chocolate?” Mika asked.
That made Mia laugh.
Then Mia remembered Angel. Angel was a researcher who often said mysterious science words like “isotopes”, “Less negative”, “More negative”. Mia was not completely sure what isotopes were, but somewhere in her vague memory she remembered Angel also talking about water vapor. Maybe Angel would know whether water in the sky could tell where it came from.
So Mia decided to ask her. “Water vapor can travel long distances with the wind. Sometimes, air brings a lot of moisture from warmer places all the way to the Arctic.” “The Arctic?” asked Mia. “That sounds very far!” .
“Yes,” Angel said. “And the Arctic is changing in many ways. So we want to understand where the water in the Arctic comes from, how it gets there, and what happens to it.”
Mika raised one paw. “But how can you know where the water vapor came from?”
Angel smiled. “That is where the mystery begins.”
Water molecules are not all exactly the same. Some are a tiny bit lighter, and some are a tiny bit heavier. Scientists call these different types of water isotopes.
“You can imagine them like water molecules wearing different backpacks,” Angel said. “Some have a light backpack, and some have a slightly heavier one.”
Water evaporates from the ocean, forms clouds, travels with the wind, or falls as snow or rain, the number of light and heavy water molecules changes a little. These tiny changes give scientists clues.
“So the water carries a kind of fingerprint?” Mia asked.
“Exactly!” said Angel. “By looking at this fingerprint, we can learn something about where the water came from and what happened to it on the way.”
Angel uses measurements from satellites high above the Earth, instruments on the ground, and models of the atmosphere made with computers. Satellites can look at large areas, including remote Arctic regions where it is difficult to measure every day. Computer models help scientists follow how air and moisture move.
Sometimes, huge streams of moist air travel northwards. They are called atmospheric rivers. They are not rivers on the ground, but rivers in the sky. They can carry lots of water vapor into the Arctic.
“That sounds like a sky river!” Mia said.
“Yes,” Angel laughed. “And I study how these sky rivers change the water vapor fingerprint in the Arctic.”
This is important because water vapor can affect clouds, snow, rain, and temperature. If more moisture reaches the Arctic, it can change the weather there and also affect snow and ice. Mia looked at the clouds again.
“So even invisible water can tell a story?”
“Yes,” said Angel. “Every cloud, snowflake, and raindrop has travelled somewhere. My job is to listen carefully to the clues hidden in the water.”
Mika looked very serious. “Then the next time it rains, I will ask the raindrops where they have been.”
Mia smiled. “And maybe they came all the way from the ocean…. Or someone’s hot chocolate!”
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Text: Angel Ignatious, Illustration: Patrizia Schoch