Measure Temperature and Rainfall

Scientists don't just watch the weather — they measure it! Two of the most important measuring tools are the thermometer and the rain gauge. Learning to read them in both °F and °C (and in inches and millimeters) turns you into a real weather observer.

The thermometer

• A thermometer measures temperature — how hot or cold the air is.
• In the United States, weather reports use degrees Fahrenheit (°F) every day.
• Scientists around the world use degrees Celsius (°C) — so weather apps and lab tools often show both scales.
• The colored liquid inside rises when it gets warmer and falls when it gets cooler.
• To read it: find the top of the colored liquid and read the nearest number on the scale.

Key temperature benchmarks (°F and °C)

• 32°F = 0°C — the freezing point of water. At or below this, water turns to ice.
• 70°F ≈ 21°C — a comfortable, warm room temperature.
• 90°F ≈ 32°C — a hot summer day.
• 98.6°F = 37°C — normal human body temperature.
• 212°F = 100°C — the boiling point of water.

The rain gauge

• A rain gauge is a clear tube placed outside to collect rainwater.
• After it rains, you read the water level on the marked scale. US weather reports use inches; scientists also use millimeters (mm) or centimeters (cm).
• Light rain: about 0.1 in (~3 mm). Heavy rain: about 1 in (~25 mm). A big storm can drop 2 in or more (~50 mm or more).
• Scientists record rainfall every day to track weather patterns over time.