Checking the Temperature and Weather Tools - First Grade Science
To understand weather and predict what will happen tomorrow, scientists do not just guess by sticking a hand outside; they collect accurate data using specialized weather tools. Weather tools are precision instruments designed to measure temperature, wind direction, wind speed, rainfall amounts, and air pressure. By recording daily measurements in weather logs, meteorologists spot patterns, track approaching storm fronts, and provide forecasts that help people plan their days and stay safe.
The Thermometer: Measuring Air Temperature
A thermometer is an instrument used to measure temperature, which tells us how hot or cold something is.
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| THE THERMOMETER |
| |
| .---. |
| | | 40 C (104 F) <--- Scorching summer day |
| |---| |
| | | 30 C (86 F) <--- Warm beach weather |
| |---| |
| | | 20 C (68 F) <--- Comfortable room temperature |
| |---| |
| | | 10 C (50 F) <--- Crisp autumn jacket weather |
| |---| |
| |===| 0 C (32 F) <--- FREEZING POINT OF WATER (Snow/Ice) |
| |===| -10 C (14 F) <--- Freezing winter coat weather |
| ( === ) |
| '---' LIQUID BULB: Red liquid expands when warm (rises) |
| and contracts when cool (drops). |
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How a Liquid Thermometer Works
Inside a glass thermometer is a thin glass tube with a bulb at the bottom filled with colored liquid (usually alcohol). When the outdoor air gets warmer, heat energy causes the liquid molecules to expand and push upward along the tube. When the air gets colder, the liquid contracts, shrinking and dropping back down. Numbers along the tube show the exact temperature in degrees Celsius (C) or degrees Fahrenheit (F).
Important Temperature Benchmarks
Water freezes into solid ice at 0 degrees Celsius (32 degrees Fahrenheit). A comfortable indoor room is about 20 degrees Celsius (68 degrees Fahrenheit). A hot summer swimming day is about 30 degrees Celsius (86 degrees Fahrenheit). Normal human body temperature is 37 degrees Celsius (98.6 degrees Fahrenheit).
The Rain Gauge: Measuring Rainfall
A rain gauge is a transparent, straight-sided cylinder marked with inches or millimeters, used to measure how much liquid precipitation falls during a storm.
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| THE RAIN GAUGE |
| |
| |\ /| |
| | \ COLLECTOR / | |
| | '-------------------' | |
| | | |
| | |-- 5 cm | |
| | |-- 4 cm | |
| | |-- 3 cm | |
| | |-- 2 cm ~~~~~~~~~~~~~ | <--- WATER LEVEL: 2 cm of rain|
| | |-- 1 cm ~~~~~~~~~~~~~ | fell during the storm! |
| +-------------------------+ |
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To use a rain gauge accurately, it must be placed outdoors in an open area away from overhanging tree branches or roof gutters that could drip extra water inside.
Measuring Wind: Direction and Speed
Meteorologists use two distinct instruments to measure the wind: the wind vane and the anemometer.
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| INSTRUMENTS FOR MEASURING WIND |
| |
| WIND VANE (Measures Direction) ANEMOMETER (Measures Speed) |
| |
| N _O_ |
| | / | \ |
| W ---+--- E O--+--O (Spinning Cups)|
| | | |
| S | <--- Spun by wind|
| Arrow points into the wind, Cups spin faster as wind speed |
| telling where wind is COMING FROM. increases; speedometer measures |
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The Wind Vane
A wind vane has a pointer arrow on top of a pivot with cardinal directions marked below (North, South, East, West). The tail of the arrow has a wide fin that catches the wind, rotating the sharp arrow tip so it points directly in the direction from which the wind is blowing. A "North wind" means the wind is coming from the cold North toward the South!
The Anemometer
An anemometer consists of three or four hemispherical cups mounted on horizontal arms that rotate freely on a vertical spindle. When wind blows, it pushes into the open hollow of the cups, spinning them around. The faster the wind blows, the faster the cups spin. A meter counts the rotations to calculate wind speed in miles per hour or kilometers per hour.
Recording Data in a Daily Weather Chart
Scientists keep daily weather logs, tracking numbers and patterns over weeks and months to see how climate changes through the seasons.
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| SAMPLE WEATHER TRACKER |
| |
| DAY TEMP (C) WIND DIR. PRECIPITATION SKY CONDITION |
| Monday 18 C West 0 mm Sunny, few clouds |
| Tuesday 14 C North 12 mm Rainy, dark clouds |
| Wednesday 16 C Northwest 2 mm Partly cloudy |
| Thursday 21 C South 0 mm Bright sunshine |
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Chapter Review Exercises
Question 1: What is a thermometer, and how does the liquid inside it show whether the air is getting hotter or colder?
Question 2: What are the freezing temperatures of water on both the Celsius and Fahrenheit temperature scales?
Question 3: How does a wind vane determine which direction the wind is blowing?
Question 4: What is an anemometer, and how does it measure the speed of the wind?
Solutions and Explanations
Solution 1: A thermometer is an instrument that measures temperature (how hot or cold something is). When air warms up, the liquid inside the bulb expands and rises up the narrow tube; when air cools down, the liquid contracts and sinks lower.
Solution 2: Water freezes into ice at 0 degrees Celsius and at 32 degrees Fahrenheit.
Solution 3: A wind vane has a tail fin that catches the wind and pivots freely. The wind pushes the tail away, causing the arrow tip to point directly into the oncoming breeze, indicating the compass direction where the wind is coming from.
Solution 4: An anemometer is a tool with curved cups mounted on rotating arms. As the wind blows, it catches in the cups and spins them around a central axis; counting the speed of rotations measures wind velocity in miles or kilometers per hour.