Weather
Name______________________ ____________________ Date________
Weather affects our lives each and every day; what we wear, where we go, do we have school or not? Every decision can be affected by the weather. We ask the meteorologist to forecast (predict) the weather; sometimes they are right and sometimes they are wrong. Forecasting the weather is no easy task.
Weather-describes the conditions in the atmosphere (mostly the troposphere the lowest layer of the atmosphere) at a given place for a short period of time
Weather – is caused by the uneven heating of the earth by the Sun’s rays
Questions: Answer in complete sentences
1. What is weather? ___________________________________________ __________________________________________________________ __________________________________________________________ 2. What causes weather? _______________________________________
_________________________________________________________ _________________________________________________________ 3. In what layer of the earth’s atmosphere does most weather occur?
Weather Variables
The change in weather is described by a series of weather variables. These weather variables include Air Temperature, Air Pressure, Humidity, Wind Speed, Wind Direction, and Precipitation
Air Temperature-the amount of heat energy in the atmosphere at a place Air Pressure- is the amount of force exerted by the air hitting a given surface area
Humidity- the amount of water vapor in the air Wind Speed-the rate of moving air
Wind Direction- the direction that the wind blows FROM
Precipitation-failing moisture from clouds (Rain, Snow, Sleet, and Hail) Scientists communicate weather in different locations using the station model .
On the station model above identify the following weather variables: 1. Temperature________0F
2. Air Pressure_______mb
Weather Variable Definition
Units
Instrument
Air Temperature The amount of heat energy in the
atmosphere as a place
0F (Fahrenheit) or 0C (Celsius)
Thermometer
Air Pressure The amount of force exerted by the air hitting a given surface area
millibars (mb) Barometer
Humidity The amount of water vapor in the air
Relative Humidity expressed in percent %
Sling
Psychrometer Wind Speed Moving air Knots or miles per hour (K
or mph)
Anemometer
Wind Direction The direction that the wind is blowing FROM
North, East, South, West Wind Vane
Precipitation Forms of water that fall from clouds example: Rain, snow, sleet, hail, or freezing rain
Instrument questions:
1. What instrument would you use to measure the wind speed? _____________ 2. What instrument would you use to measure wind direction?____________ 3. What instrument would you use to measure air temperature?____________ 4. What are the units for air pressure?________________________
5. What are 4 types of precipitation?1. ________________2. __________ 3.____________________ 4__________________________
6. Why is wind direction misleading? ____________________________ _________________________________________________________ 7. What instrument do you use to measure air pressure?___________________ 8. What instrument do you use to measure humidity?_____________________
9. 10.
11.The change from water vapor to liquid water is called a. evaporation
c. melting
Wind
Wind- horizontal movement of air which is caused by differences in air pressure. Air moves from HIGH PRESSURE to LOW PRESSURE! The differences in pressure are caused by uneven heating of the earth!
HOT AIR RISES=LOW PRESSURE COLD AIR SINKS= HIGH PRESSURE Wind direction- the direction that the wind is coming from
Example: the wind is coming from the west so the wind direction is WEST Example 2: the wind is from the north so the wind direction is NORTH Example 3: the wind is blowing to the east so the wind direction is WEST Wind Speed-the rate at which wind moves in knots or mph
NOTE: Winds appear to curve to the right in the northern hemisphere. This is caused by the earth’s rotation and is known as the Coriolis Effect
Wind Questions:
1. What causes wind? ___________________________________________ 2. Hot air _______________ and cold air _____________________
3. Hot air is associated with _____________________ pressure. 4. Cold air is associated with ____________________ pressure.
5. Explain the relationship between wind speed and differences in air pressure. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ 6. The wind is blowing to the north. What is the wind direction?___________ 7. What is the wind direction on this station model?________
8. As air circulates this is known as what type of energy transfer? a. Conduction
b. Convection c. Radiation
HIGH
PRESSURE
LOW
9. Which factor most directly affects the wind speed between two locations? a. Cloud cover
b. Time of day c. Air pressure
10.Wind appears to curve to the _______________ in the northern hemisphere a. Left
b. Up c. Right
11.The curving of wind in the northern hemisphere to the right is known as a. Coriolis Effect
b. Pressure c. Temperature
Clouds, precipitation and dew point
Dew Point- the temperature at which water vapor condenses out of the air because the air is saturated
Q. How do clouds form?
A. Clouds form when air is cooled to the dew point and water condenses into tiny water droplets or ice crystals. In-order for water vapor to condense it must have a surface to condense on. These surfaces are known as
condensation nuclei. Some examples of this are dust or ice. Q. How does precipitation occur?
A. Once the water droplets or ice crystals are too large they fall to the ground as precipitation. They type of precipitation depends on the atmospheric conditions in the clouds and on the ground!
Different types of clouds form depending on the altitude and conditions Dark= Precipitation
Some examples: Cirrus- High wispy clouds
Cumulus- low puffy clouds
Cumulonimbus- tall dark thunderstorm clouds
Stratus-flat low clouds (gloomy)
Cloud Questions: (Answer in complete sentences) 1. What causes a cloud to form?
2. What is the dew point?
3. Why do you think dew forms on the grass in the morning?
4. How does precipitation occur?
6. Why is fog not a form of precipitation?
Field Maps and Isolines
Meteorologists measure weather variables all over the country. The meteorologists take all these data and place them on a large map known as a field map.
Field Map- a region of space that has a measurable quantity or value at every point The meteorologists then connect points with the same values…
Isobars- lines of equal air pressure
Questions( Answer in complete sentences)
1. What is a field map?
2. What is an isoline? Provide an example?
3. Based on your knowledge of wind; will wind go into or out of a Low? Why?
Isotherm: lines of equal temperature
Isotherm questions:
1. Where are temperatures the highest and where are they the lowest? Explain using the words north, south, high latitude and low latitude.
2. What is an isotherm?
3. An air mass that forms over water would be dry or moist?_______________ 4. An air mass that forms over land would be dry or moist?_______________
Weather forecasts are based on the movements of air masses. By observing and predicting their paths meteorologists and forecast the weather to help you plan your daily activities and decisions.
Air Mass- air with generally uniform characteristics Source Region- the surface over which an air mass forms Front- The boundary (on the ground) between two air masses
Arctic: A Polar: P Tropical: T
Formed over extremely cold , ice covered regions
Formed over regions of high latitudes where temperatures are relatively low
Formed over regions of low latitudes where temperatures are relatively high maritime: m Formed over water, moist
mP- cold, moist Formed over North Atlantic, North Pacific
mT-warm, moist Formed over Gulf of Mexico,
middle Atlantic, Caribbean, Pacific (south of California)
continental: c Formed over land, dry
cA- dry, frigid Formed north of Canada
cP- cold, dry Formed over northern and central Canada
Ct- warm, dry formed over southwestern United States in summer
Question:
2. Label the air masses below (hint there is not cA on the map)
3. Relative to position 2 on the map; where would a cA air mass form? Place a STAR in this location!
4. What is the temperature, wind direction and wind speed of this station model?
a. Temperature_________ F b. Wind Direction ________ c. Wind Speed __________ knots d. Pressure __________ mb
5. Between which two letters will the wind speed be the greatest? Why? a. A-B
b. C-B c. D-E Why?
Fronts are where major changes in weather occur, cold air mass replaces a warm air mass the weather changes. Violent weather occurs at these
locations including rain, strong winds, and abrupt changes in temperatures. Air masses typically move from WEST to EAST across the United States. The weather that occurred in Chicago today will be in New York tomorrow! Front- the line on the ground marking the boundary between two air masses Cold Front- the ground location where a cold air mass advances against a warmer air mass. The cold air mass is denser so it forces the warm up rapidly. This causes the warm air rise, expand and cool. This rapid condensation leads to heavy rain and/or thunderstorms. The temperature drops rapidly as a cold front passes!
The cold front symbol
the cold air. As the warm air rises it expands, and cools. This causes condensation to occur over a wide gently sloping boundary. This results in thick clouds and widespread precipitation.
Warm front symbol
Questions:
1. What happens to the temperature as a cold front passes?
2. What type of precipitation do you get with a warm front?
3. Why does the warm air rise up and over the cold air at a cold front?
4. Draw the front symbols on the map from B-C and B-D!
Weather is extreme. Weather brings floods, causes landslides, and delivers hurricanes, tornados, thunder and lightning. Weather destroys homes, roads, and even the beach. Your life may be at risk from the weather!
Cyclone- any inward and counterclockwise air circulation around a low pressure center
Hurricane: -are huge cyclonic storms (Low Pressure systems) that form in the summer over warm
ocean water. The energy from a hurricane comes from the sun as it evaporates water to fuel the hurricane! The wind blows counterclockwise around the center! Winds can blow from 74 -200+mph! Hurricanes can be larger than 500 km diameter! Coastal flooding and winds cause extensive damage during a hurricane!
Questions:
1. How do winds blow around a hurricane?
2. What fuels a hurricane and gives it its power!
1. What cause the clouds and precipitation to form on the windward side of the mountain?
a. Sinking, contracting, warming air b. Rising expanding and cooling air
2. Wind blows from____________ pressure to ________________ pressure.
3. A(n) ________________________ is used to measure wind speed.
4. What type of front is shown here: a. Cold front
b. Warm front
5. Why is the warm air forced up in a cold front?
_________________________ __________________________ __________________________
6. Weather mostly occurs in the ____________________ the lowest layer of the atmosphere.
7. What type of front is shown here: a. Warm front
8. Draw in the 10, 15, 20 and 250C isotherm on the field map:
9. An isoline of equal pressure is known as a_______________
10.Identify the variables form the station model: a. Wind Speed and direction
________knots _________(direction) b. Temperature ____________F
c. Pressure ____________mb
11.The lines 992, 996, and 1000 are lines of equal _________________ known as
