2. UNIT 1: Weather Dynamics Chapter 1: Inquiring about Weather Chapter 2: Weather Forecasting 2.1 – Measuring Weather Data

3. Chapter 2: Weather Forecasting UNIT 1 Chapter 2: Weather Forecasting TO PREVIOUS SLIDE The east coast of Canada has been called one of the foggiest places in the world. When is it important to know information about fog and visibility?

4. 2.1 Measuring Weather Data UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Our control over weather is limited, but meteorologists are able to measure, record, and communicate weather conditions in great detail. Weather forecasting is the process of predicting future weather based on observations of atmospheric conditions. This photo shows cloud seeding equipment on the wing of an airplane. Why would someone want to seed clouds?

5. Measuring the Components of Weather UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Meteorologists collect data on temperature wind speed and direction Humidity air pressure precipitation other components of weather.

6. Measuring the Components of Weather UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE There are two types of observations. Qualitative observations involve the senses, such as how the sun feels on the skin, the sound made by wind, and how clear (or foggy) the sky looks. Quantitative observations involve measuring the physical conditions of the atmosphere with a variety of instruments.

7. Measuring Temperature UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE What is the device on the right, and what does it do? How does a thermometer work? Galileo invented the first device to measure temperature variations in 1593. Two modern ways to measure temperature are the thermometer and the thermoresistor. How does a thermoresistor work?

8. Measuring Precipitation UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Rainfall is measured using a rain gauge or a tipping bucket rain gauge. Snow is measured using a stick or pole that is marked vertically with units such as centimetres. Snowfall is also measured by melting it and measuring the amount of water it contains. How does the tipping bucket rain gauge, shown on the right, work?

9. Measuring Atmospheric Pressure UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Atmospheric pressure is measured with a barometer. Modern mercury barometers work on the same principle as the one invented by Evangelista Torricelli in 1644. Electronic sensors and aneroid barometers also measure atmospheric pressure. Describe in your own words how a mercury barometer works. How does an aneroid barometer work?

10. Measuring Humidity UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDEPREVIOUS Hygrometers are used to measure relative humidity. There are three common types of hygrometers: sling psychrometer analog hygrometer digital hygrometer How do each of these devices measure humidity?

11. Humidity and the Humidex Scale UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Relative humidity readings are compared to temperature values on a humidex scale. What does this scale indicate?

12. Meteorologists measure two aspects of wind: wind speed and wind direction. Wind speed is the speed at which air is moving through the atmosphere parallel to the ground. Meteorologists measure wind speed with an anemometer. Wind direction is measured with a wind vane. Measuring Wind Speed and Direction UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Continued…

13. Measuring Wind Speed and Direction UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Continued… Wind direction measurements are expressed using sixteen compass directions to indicate the direction from which the wind is blowing.

14. Measuring Wind Speed and Direction UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Wind speed can be measured without instruments using the Beaufort scale. Why do the descriptions have so many references to ocean behavior?

15. Weather Observation Systems UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Meteorologists use a variety of instruments to measure atmospheric conditions. There are three primary devices used. weather balloons weather radar weather satellites What is a radiosonde? How does it work? What is Doppler radar? What are weather satellites?

16. Section 2.1 Review UNIT 1 Chapter 2: Weather Forecasting Section 2.1 TO PREVIOUS SLIDE Weather measurement and record-keeping are part of weather forecasting. Mechanical and digital devices are used to measure weather. The humidex scale is used to determine what temperatures feel like as relative humidity changes. The Beaufort wind scale equates qualitative observations with quantitative wind speed measurements. Radar and satellite remote sensing technology collect weather data from a distance.