Transcript Weather Patterns
Weather Patterns
Table of Contents
Air Masses and Fronts Storms Predicting the Weather
Weather Patterns
- Air Masses and Fronts
Classifying Air Masses
Four major types of air masses influence the weather in North America: maritime tropical, continental tropical, maritime polar, and continental polar.
Weather Patterns
- Air Masses and Fronts
Types of Air Masses
Air masses can be warm or cold, and humid or dry. As an air mass moves into an area, the weather changes.
Weather Patterns
- Air Masses and Fronts
How a Front Forms
The boundary where unlike air masses meet is called a
front
.
Weather Patterns
- Air Masses and Fronts
Types of Fronts
Colliding air masses can form four types of fronts: cold fronts, warm fronts, stationary fronts, and occluded fronts.
Weather Patterns
- Air Masses and Fronts
Weather Fronts Activity
Click the Active Art button to open a browser window and access Active Art about weather fronts.
Weather Patterns
- Air Masses and Fronts
Cyclones and Anticyclones
Winds spiral inward towards the low-pressure center of a cyclone. Winds spiral outward from the high-pressure center of an anticyclone.
Weather Patterns
- Air Masses and Fronts
Comparing and Contrasting
As you read, compare and contrast the four types of fronts by completing a table like the one below.
Front
Cold front Warm front Stationary front Occluded front
How It Forms Types of Weather
A cold air mass overtakes a warm air mass.
A warm air mass overtakes a cold air mass.
Clouds, possibly storms with heavy precipitation Clouds, light precipitation Cold and warm air masses meet, but neither can move the other.
Clouds, precipitation A warm air mass is caught Clouds, precipitation between two cold air masses.
Weather Patterns
End of Section: Air Masses and Fronts
Weather Patterns
- Storms
Thunderstorm Formation
A thunderstorm forms when warm, humid air rises rapidly within a cumulonimbus cloud.
Weather Patterns
- Storms
Tornado Formation
Tornadoes can form when warm, humid air rises rapidly in thick cumulonimbus clouds —the same type of clouds that bring thunderstorms.
Weather Patterns
- Storms
Tornado Alley
Tornadoes in the U.S. are most likely to occur in a region known as Tornado Alley.
Weather Patterns
- Storms
Structure of a Hurricane
In a hurricane, air moves rapidly around a low-pressure area called the
eye
.
Weather Patterns
- Storms
Hurricane Andrew
The path of Hurricane Andrew over three consecutive days can be seen below.
Weather Patterns
- Storms
Lake-Effect Snow
As cold dry air moves across the warmer water, it becomes more humid as water vapor evaporates from the lake surface. When the air reaches land and cools, snow falls.
Weather Patterns
- Storms
Sequencing
As you read, make a flowchart like the one below that shows how a hurricane forms. Write each step of the process in a separate box in the order in which it occurs.
Hurricane Formation
Begins as a low-pressure area over warm water, or a tropical disturbance.
Warm, humid air rises and begins to spiral.
As air rises, more warm, moist air is drawn into the system and the hurricane gains energy.
As winds spiral inward, bands of high winds and heavy rains form.
Weather Patterns
- Storms
More on Thunder and Lightning
Click the Planet Diary button for an activity about thunder and lightning.
Weather Patterns
- Storms
Tornadoes
Click the Video button to watch a movie about tornadoes.
Weather Patterns
- Storms
Hurricanes
Click the Video button to watch a movie about hurricanes.
Weather Patterns
End of Section: Storms
Weather Patterns
- Predicting the Weather
Red Sky
A red sky is one kind of observation that helps people to predict the weather.
Weather Patterns
- Predicting the Weather
Computer Weather Forecasting
Scientists use computers to develop different models of how a front may move. These predictions are then used to make weather forecasts. As more data become available, some models are found to be incorrect, while others are found to closely fit the predicted conditions. The upper graph shows the predicted air pressure from two models. The lower graph shows actual data for air pressure.
Weather Patterns
- Predicting the Weather
Computer Weather Forecasting Reading Graphs:
What two variables are being graphed?
Time of day and air pressure
Weather Patterns
- Predicting the Weather
Computer Weather Forecasting Interpreting Data:
How is air pressure predicted to change according to each model in the top graph?
According to model A, air pressure will drop slightly then increase. According to model B, air pressure will steadily decrease.
Weather Patterns
- Predicting the Weather
Computer Weather Forecasting Inferring:
Which computer model most closely matches the actual air pressure data?
Model B
Weather Patterns
- Predicting the Weather
Computer Weather Forecasting Predicting:
What weather would you forecast for Monday and Tuesday? Explain.
Stormy weather, clouds, and precipitation accompany low air pressure.
Weather Patterns
- Predicting the Weather
Reading Weather Map Symbols
The figure below shows what various weather symbols mean.
Weather Patterns
- Predicting the Weather
Reading Weather Maps
This is the type of weather map produced by the National Weather Service. It shows data collected from many weather stations.
Weather Patterns
- Predicting the Weather
Reading Weather Maps
Weather maps in newspapers use symbols to show fronts, high- and low-pressure areas, and precipitation. Color bands indicate different temperature ranges.
Weather Patterns
- Predicting the Weather
Previewing Visuals
Before you read, preview Figure 21, a weather map. Then write four questions that you have about the map in a graphic organizer like the one below. As you read, answer your questions.
Previewing Figure 21 Q
. What type of front is located west of Okalahoma City?
A
. A cold front
Q
. What do the stick symbols indicate?
A
. Amount of cloud cover, atmospheric pressure, wind direction and speed, and temperature
Q
. What are the slender, curvy lines?
A
. Isobars, which join places with the same air pressure
Q
. What does the symbol to the east of Florida mean?
A
. A hurricane
Weather Patterns
- Predicting the Weather
More on Weather Maps
Click the Planet Diary button for an activity about weather maps.
Weather Patterns More on Doppler Radar
Click the PHSchool.com button for an activity about Doppler radar.
Weather Patterns
End of Section: Predicting the Weather
Weather Patterns Graphic Organizer Type of Storm Where Forms Typical Time of Year Safety Rules
Thunderstorms Within large cumulonimbus clouds Spring or Summer Seek shelter, avoid trees and water.
Tornado Hurricane Cumulonimbus cloud Over warm ocean water Spring, early summer Move to a storm shelter or basement if possible; stay away from windows and doors.
Late summer and into autumn Evacuate or move inside a well-built building.
Weather Patterns