2. Weather is the daily conditions of the atmosphere. Weather forms in the lowest layer of the atmosphere, the troposphere. To describe weather, scientists study 4 properties: 1.air temperature 2.humidity 3.air pressure 4.wind

3. Air temperature- caused by the amount of direct sunlight that is heating the Earth’s surface More sunlight = higher, warmer temperatures. Humidity- the amount of water vapor in the air More water vapor = higher humidity = the air feels more damp and sticky

4. Thermometers are used to measure the air temperature of an area. Two temperature measurement systems: Fahrenheit and Celsius. SystemBoiling PointFreezing Point FahrenheitCustomary212°32° CelsiusMetric100°0°

5. A hygrometer is used to measure humidity, or the amount of water vapor in the air. Hygrometers can be analog or digital.

6. Air has weight and it pushes onto the Earth’s surface. Air pressure- the force put on an area by the weight of the air above it The particles of cool air are closer together. Cool air is heavier and has higher air pressure. The particles of warm air are spread farther apart. Warm air weighs less and has lower air pressure. In other words, cool air and warm air

7. A barometer is used to measure air pressure. Air pressure is also called atmospheric pressure.

8. Air in motion is called wind. Wind is caused by the uneven heating of the Earth’s surface. Different parts of the Earth’s surface absorb different amounts of the sun’s energy, so the temperatures are different. Air moves from high pressure places (cool air places) to low pressure place (warm air places).

9. WIND During the day, the land heats up faster. The water is cooler than the land, so the wind blows towards the land. At night, the land cools off pretty quick. The land is cooler than the water, so the wind changes direction.

10. An anemometer measures wind speed. The wind is caught in the cup-looking devices and it begins spinning. A weather vane, or wind vane, tells you which way the wind is blowing. Think opposites: if the vane is pointing east, the wind must be coming from the opposite direction, or the west.

11. Rain gauges collect precipitation as it falls. A rain gauge can be made with many different materials. For example, any clear container with measurement markings on the outside would work as a rain gauge.