Fun weather-themed crossword puzzle for kids.

To solve the crossword puzzle, we need to identify terms related to weather and atmospheric phenomena. Below is the solution with explanations for each clue:

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Across:

1. Prediction of what the weather will be.
- Answer: FORECAST
- Explanation: A forecast is a prediction of future weather conditions.

2. Balls of frozen rain.
- Answer: HAIL
- Explanation: Hail consists of balls or lumps of ice that form during thunderstorms.

3. Precipitation that falls as water droplets.
- Answer: RAIN
- Explanation: Rain is liquid precipitation that falls from clouds.

4. Amount of water vapor in the air.
- Answer: HUMIDITY
- Explanation: Humidity refers to the amount of water vapor present in the air.

5. Tool that measures the amount of precipitation.
- Answer: RAINGAUGE
- Explanation: A raingauge is used to measure the amount of rainfall over a specific period.

6. Line where two air masses meet.
- Answer: FRONT
- Explanation: A front is the boundary between two different air masses, often leading to weather changes.

7. Process by which water vapor forms into clouds.
- Answer: CONDENSATION
- Explanation: Condensation occurs when water vapor cools and changes into liquid droplets, forming clouds.

8. Layer of the atmosphere that contains most of our weather.
- Answer: TROPOSPHERE
- Explanation: The troposphere is the lowest layer of Earth's atmosphere, where most weather occurs.

9. Clouds of air with small water droplets that float above the ground.
- Answer: FOG
- Explanation: Fog is a cloud that forms near the ground, consisting of tiny water droplets.

10. Moving air.
- Answer: WIND
- Explanation: Wind is the movement of air from areas of high pressure to areas of low pressure.

11. Currents of air circulating the earth.
- Answer: JET STREAM
- Explanation: Jet streams are fast-moving ribbons of air in the upper atmosphere that influence weather patterns.

12. Rain that contains some acid.
- Answer: ACID RAIN
- Explanation: Acid rain is precipitation with elevated levels of acidity, caused by pollutants like sulfur dioxide and nitrogen oxides.

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Down:

1. Atmospheric moisture.
- Answer: WATER VAPOR
- Explanation: Water vapor is the gaseous state of water in the atmosphere.

2. Excluding colors of air with no clouds.
- Answer: CLEAR SKY
- Explanation: A clear sky has no clouds, allowing sunlight to pass through without obstruction.

3. Changing of a liquid to a gas.
- Answer: EVAPORATION
- Explanation: Evaporation is the process by which a liquid (like water) turns into a gas (water vapor).

4. Air mass that causes a hurricane.
- Answer: LOW PRESSURE SYSTEM
- Explanation: Hurricanes form around low-pressure systems, where air spirals inward and upward.

5. Warm air rising.
- Answer: CONVECTION
- Explanation: Convection occurs when warm air rises due to its lower density compared to cooler air.

6. Hot air current.
- Answer: UPDRAFT
- Explanation: An updraft is a column of rising air, often associated with thunderstorms.

7. Rain that falls on land.
- Answer: PRECIPITATION
- Explanation: Precipitation includes any form of water falling from the sky, such as rain, snow, sleet, or hail.

8. Strong wind storm with heavy rain.
- Answer: THUNDERSTORM
- Explanation: A thunderstorm is characterized by strong winds, heavy rain, lightning, and thunder.

9. Violent rotating column of air.
- Answer: TORNADO
- Explanation: A tornado is a violent, rotating column of air that extends from a thunderstorm to the ground.

10. Wind blowing at 74 mph or more.
- Answer: HURRICANE
- Explanation: A hurricane is a tropical cyclone with sustained winds of 74 mph or higher.

11. Rain that falls as ice crystals.
- Answer: SNOW
- Explanation: Snow is precipitation that falls as ice crystals.

12. Water droplets suspended in the air.
- Answer: CLOUDS
- Explanation: Clouds are collections of tiny water droplets or ice crystals suspended in the atmosphere.

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Final Answer:

The completed crossword puzzle is as follows:

```
F O R E C A S T
H A I L
R A I N
H U M I D I T Y
R A I N G A U G E
F R O N T
C O N D E N S A T I O N
T R O P O S P H E R E
F O G
W I N D
J E T S T R E A M
A C I D R A I N
W A T E R V A P O R
C L E A R S K Y
E V A P O R A T I O N
L O W P R E S S U R E S Y S T E M
C O N V E C T I O N
U P D R A F T
P R E C I P I T A T I O N
T H U N D E R S T O R M
T O R N A D O
H U R R I C A N E
S N O W
C L O U D S
```

Boxed Answer (Center):
RAINGAUGE

Thus, the final answer is:
\boxed{RAINGAUGE}