How is weather predicted? D18-23 V. Martinez 1. Meteorologist • A meteorologist is a scientist who studies and measures weather conditions. 2. Thermometer • A thermometer measures the temperature of the air. 3. barometer • A barometer measures air pressure. 4. anemometer • An anemometer is used to measure wind speed. 5. Weather Vane • A weather vane or wind sock is used to measure wind direction. 6. hygrometer • A hygrometer measures moisture in the air or the humidity. 7. Humidity • Humidity is the amount of water vapor in the air. 8. Land heats faster than bodies of water. So the air above land is usually warmer. 9. What affects humidity? • 1. The area over which an air mass forms: An air mass over water has more water than an air mass over land. • 2. Temperature: Warm air has more moisture than cool air. 10. Scientists record weather information to predict changes in weather. 11. Small vertical dashes on a weather map stand for rain. 12. Small stars on a weather map stand for snow. 13. Rain falls from clouds when water droplets in the clouds become big and heavy. 14. On the barometer, when air pressure drops, the air in the jar expands and pushes up against the balloon, causing the craft stick to point downward. 15. On the barometer, when air pressure rises, the air surrounding the jar pushes down on the balloon, which causes the craft stick to point up.