UNIT 1: Weather Dynamics

Chapter 1: Inquiring about Weather

Chapter 2: Weather Forecasting

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?

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?

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, and other components of weather. 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.

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?

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?

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 barometerwork?

Measuring Humidity

UNIT 1 Chapter 2: Weather Forecasting Section 2.1

TO PREVIOUS SLIDE

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 devicesmeasure humidity?

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?

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…

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.

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?

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?

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.

2.2 Forecasting the Weather

UNIT 1 Chapter 2: Weather Forecasting Section 2.2

TO PREVIOUS SLIDE

By observing trends and patterns in weather data, meteorologists are able to make both short-range forecasts (ranging up to 48 hours) and extended or long-range forecasts (ranging from 3 to 7 days).

•A short-range forecast is a forecast that predicts how weather conditions will change over a period of up to 48 hours.•A long-range forecast is a forecast that predicts how weather conditions will change over a period of 3 to 7 days.

Short-range Weather Forecasts

UNIT 1 Chapter 2: Weather Forecasting Section 2.2

TO PREVIOUS SLIDE

• The simplest form of short-range weather forecast is called persistence forecasting, which assumes that current weather patterns will persist for up to a few hours.

• Nowcasting relies on remote sensing technology and forecasts weather for up to about 6 hours.

Weather Symbols and MapsUNIT 1 Chapter 2: Weather Forecasting Section 2.2

TO PREVIOUS SLIDE

On the weather map, what does the red symbol on top of Nova Scotia mean?

Continued…

Weather Symbols and MapsUNIT 1 Chapter 2: Weather Forecasting Section 2.2

TO PREVIOUS SLIDE

• Meteorologists combine data recorded by various weather stations to create weather maps.

• The location of weather fronts, as well as the speed and direction of the front, is important in short-range weather forecasting.

• Long-range forecasting relies on computer-based statistical analysis of past weather data and computer models of atmospheric circulation and behaviour.

• What is the main reason that computermodels, like the one shown on the right,are sometimes inaccurate?

Section 2.2 Review

UNIT 1 Chapter 2: Weather Forecasting Section 2.2

TO PREVIOUS SLIDE

• Meteorologists observe trends and patterns to make short-range (up to 48 hours) and long-range forecasts (from 3 to 7 days).

• Weather maps use symbols to communicate weather conditions.

• Short-range weather forecasts are more reliable than long-range forecasts.

2.3 Importance and Limitations of Weather Forecasting

UNIT 1 Chapter 2: Weather Forecasting Section 2.3

TO PREVIOUS SLIDE

Because of its location in the mid-latitudes, Canada experiences a wide variety of weather, much of which can be extreme and hazardous.

Identify the extreme weatherthat is occurringin each photo.

How Weather Influences Our Lives

UNIT 1 Chapter 2: Weather Forecasting Section 2.3

TO PREVIOUS SLIDE

• Biometeorology is the branch of science that studies how weather affects human health.

• Accurate weather forecasting reduces illnesses and fatalities due to extreme weather.

• Our food supply depends to a large degree on favourable weather conditions.

Continued…

What are some examples of how weather effects human health?

How Weather Influences Our Lives

UNIT 1 Chapter 2: Weather Forecasting Section 2.3

TO PREVIOUS SLIDE

• People who work in marine industries such as fishing and offshore oil development face high risks for injuries and fatalities.

• Forest fires cause many millions of dollars annually in losses to the forest industry, and they destroy wildlife habits.

• Bad weather and poor road conditions are responsible for a great number of traffic accidents and significant road damage each year.

What are some ways in which weather can cause or contributeto marine injuries and fatalities,forest fires, and traffic accidents?

The Importance of Weather Forecasting

UNIT 1 Chapter 2: Weather Forecasting Section 2.3

TO PREVIOUS SLIDE

• Accurate weather forecasts improve the ability to prepare for severe weather and increase the survival rate.

• The Meteorological Service of Canada prepares weather forecasts for Canadians.

• Canadian Hurricane Centre tracks hurricanes and tropical storms and issues warnings and advisories when extreme weather is likely.

In which governmental agency does the Meteorological Service of Canada reside?

Limitations of Weather Forecasting

UNIT 1 Chapter 2: Weather Forecasting Section 2.3

TO PREVIOUS SLIDE

• Accurate weather forecasting is difficult because there are many factors involved.

• All weather forecasts have a certain degree of uncertainty.• New technology has improved the ability to forecast weather

farther in the future.

What is the primary factor that contributes to the uncertainty of weather forecasts?

Section 2.3 Review

UNIT 1 Chapter 2: Weather Forecasting Section 2.3

TO PREVIOUS SLIDE

• Weather forecasting influences choices made on a personal, local, and national level.

• Weather affects human health as well as industries such as agriculture, marine industries, forestry, and transportation.

• Accurate forecasts allow people to prepare for future weather conditions.