Chapter 2 Study Guide: Weather factors
VOCABULARY:
Section 1: Energy in the Atmosphere
Electromagnetic waves: a form of energy that can travel through space
Radiation: transfer of energy (heat) from one object to another without heating the space between
Infrared Radiation: form of energy with wavelengths that are longer than red light
Ultraviolet Radiation: form of energy with wavelengths that are shorter than violet light
Scattering: reflection of light in all directions
Greenhouse effect: process by which gases hold heat in the air
Greenhouse gases: gases that hold Earth’s heat
Section 2: Heat Transfer
Thermal Energy: Total energy of motion in the molecules of a substance
Temperature: average amount of energy of motion of each molecule of a substance
Thermometer: instrument that measures air temperature
Heat: energy transferred from a hotter object to a colder object
Conduction: transfer of heat from one substance to another substance it is touching
Convection: transfer of heat by the movement of a fluid
Section 3: Winds
Wind: the horizontal movement of air
Anemometer: instrument used to measure wind speed
Wind-chill factor: increased cooling caused by the wind
Wind Vane: an instrument used to measure the direction of the wind (points in the direction the wind came from)
Local winds: winds that blow over short distances
 Sea Breeze: wind that blows from an ocean or lake onto land
 Land Breeze: wind that blows from the land to an ocean or lake
Monsoons: sea or land breeze over a large area that change directions with the seasons
Global winds: winds that blow over long distances
Coriolis Effect: the way Earth’s rotation causes global winds to curve
Jet streams: band of high speed winds 10km above the Earth’s surface
Section 4: Water in the Atmosphere
Evaporation: the state change where a LIQUID turns into a GAS by ADDING heat
Humidity: amount of moisture in the air
Relative Humidity: amount of moisture (water vapor) in the air compared to the amount of water vapor it can hold
Psychrometer: instrument used to measure relative humidity
Condensation: the state change where a GAS turns into a LIQUID by REMOVING heat
Deposition: the state change where a GAS turns directly into a SOLID by REMOVING heat (a lot quickly)
Sublimation: the state change where a SOLID turns directly into a GAS by ADDING heat (a lot quickly)
Freezing: the state change where a LIQUID turns into a SOLID by REMOVING heat
Melting: the state change where a SOLID turns into a LIQUID by ADDING heat
Dew Point: temperature at which condensation begins
Cumulus: clouds that form less than 2km above the ground; look like fluffy, rounded piles of cotton
Stratus: clouds that form in flat layers
Cirrus: clouds that form at high levels above 6km; wispy, feathery clouds made mostly of ice crystals
Fog: Clouds that form at or near the ground
Cumulonimbus: Looks like towering clouds sometimes with flat-tops, Indicates thunderstorms, possible hail and/or tornadoes
Nimbostratus: large, dark layers that cover the entire sky, indicates rain, snow, or sleet
Transpiration: adding water to the atmosphere through plants
Water cycle: movement of water between surfaces and the atmosphere
Section 5: Precipitation
Precipitation: any form of water that falls from clouds and reaches Earth’s surface
Rain Gauge: open-ended can or tube that collects rainfall
Drought: long periods of unusually low precipitation
Rain: water droplets, at least .5 mm
Snow: water vapor in a cloud that is converted directly into ice crystals, 6 sided
Sleet: raindrops freeze into tiny particles of ice as they fall through the air
Hail: ice pellets add layers of ice as they are carried up and down in a cumulonimbus cloud
Freezing Rain: raindrops freeze after they hit the ground and other surfaces
Glaze: layer of ice that results from freezing rain
REVIEW QUESTIONS:
Section 1: Energy in the Atmosphere
 What is visible light?
o Radiation in the form of light that can be seen (The colors of the rainbow).
 Which parts of visible light have the longest wavelengths? Shortest wavelengths?
o Longest=red, shortest=violet
 What are the affects of ultraviolet radiation and infrared radiation?
o Ultraviolet- Skin/eye damage, sunburn , Infrared- Heat
 Describe why the sky is blue/why sunsets are red.
o The sky is blue because scattered light is blue. Sunsets are red because red wavelengths (longest) can travel through
more of the atmosphere.
Section 2: Heat Transfer
 List the 3 ways that heat can be transferred.
o radiation, convection, and conduction.
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Give examples of each type of heat transfer.
o Conduction: Heating pad, curling iron, burning your feet on the hot sand
o Convection: Fluid moving in a lava lamp, water boiling in a pot, air circulating through a room, convection oven
o Radiation: Sun heating the Earth’s surface, a fire warming your hands, microwave
Explain why warm air rises and cool air sinks.
o Air near the ground is heated by the sun (radiation), The molecules gain energy and move faster. As they bump into
each other they move further apart (air expands) and become less dense. The less dense air then rises due to the
warm temperature. Cooler, denser air sinks. This causes a constant movement of heat through the troposphere
called convection current!!
How do the three types of heat transfer work together to heat the troposphere?
o Only some air near the Earth’s surface is warmed by radiation and conduction of heat from the surface to the air.
What type of heat transfer causes most of the heating in the troposphere?
o Convection causes most of the heating of the troposphere
Section 3: Winds
 Name two examples of local winds.
o Local winds are sea breezes and land breezes
 What are the global wind belts? What are the areas of calm air (either rising or falling air)? What causes global winds?
o The major global wind belts are the trade winds (equator-30° N & S latitudes), the prevailing westerlies (30° latitude
to 60° latitude), and the polar easterlies (60° latitude to the edge of the poles). The areas of calm air are the
doldrums (30°N and south latitudes), horse latitudes (60° N & S latitudes), and polar fronts. The way Earth’s rotation
causes global winds to curve.
 How are winds named?
o Winds are named for the direction they blow from
 Explain the difference between a land breeze and sea breeze.
o During the day the land gets warmer than the water. This unequal heating causes the air above the land to become
warmer than the air over the water. This air over the land rises because the molecules have more heat, are moving
quicker, and spread apart. This causes the air to become less dense. As the air rises the cool air above the water
moves in to replace it. This causes the wind to move horizontally from the sea to the land. This is an example of a
convection current.
o At night water holds heat and the land gets cooler. This unequal heating causes the air above the water to become
warmer than the air over the land. This air over the water rises because the molecules have more heat, are moving
quicker, and spread apart. This causes the air to become less dense. As the air rises the cool air above the land
moves in to replace it. This causes the wind to move horizontally from the land to the sea. This is an example of a
convection current.
 How do land and sea breezes relate or compare to monsoons?
o Sea breezes are similar to summer monsoons (winds blow from sea to land) and land breezes are similar to winter
monsoons (winds blow from land to sea)
 Explain what causes all winds.
o Unequal heating and cooling.
Section 4: Water in the Atmosphere List and describe the steps of the water cycle, starting with evaporation.
o Evaporation from oceans, lakes and streams puts water vapor into the air.
o Water vapor cools and condenses to form clouds.
o Rain and other forms of precipitation fall to the earth.
o Water then runs into the ground or off the surface into oceans lakes and streams.
o Process repeats.
 Name the three types of clouds and describe the characteristics of each type.
o Cumulus
 Clouds that form less than 2km above the ground
 Fluffy, rounded piles of cotton
 Indicate fair weather
 Cumulonimbus clouds produce thunderstorms
 Cirrocumulus clouds look like rows of cotton balls and indicate that storms are on the way
o Stratus
 Form in flat layers
 “Strato” means spread out
 Usually cover all or most of the sky
 When thickened they may produce drizzle, rain, or snow and are then called nimbostratus clouds
o Cirrus
 Wispy, feathery clouds with feathery hooked ends
 Form at high levels (6km or higher) and at low temperatures
 Made of ice crystals
 Know the state changes. (See vocab. section)
o Melting, Freezing, Condensation, Evaporation, Sublimation, Deposition
 What is the difference between humidity and relative humidity?
o Humidity is the amount of water vapor in the air and relative humidity is the amount of water vapor compared to the
amount it can hold.
 Explain how clouds form.
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Water Vapor Rises
It Cools
Condenses to
Create Clouds (at the dew point)
WV
, CCCC
What happens to air as it passes over a mountain chain?
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Global winds constantly push air in the same direction, so wind always hits the windward side of the mountain first
Air can’t go through the mountain chain so it is forced upwards
The water vapor also rises
As it rises it cools (rising though the troposphere and losing heat)
When it reaches the dew point, the water vapor condenses into cloud droplets
As the air (now with clouds) continues up the mountain it cools more and cold air can hold less moisture than warm air, so…
The moisture falls out as precipitation
The air is now drier (lost much of the moisture)
As it flows down the mountain-side, it warms up (warm air hold more moisture than cooler air), so…
No precipitation falls leaving…Desert or desert-like conditions (DRY)
Section 5: Precipitation
 Describe the differences between the 5 main types of precipitation.
Rain
Sleet
Freezing Rain
Hail
Snow
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Water droplets, at least .5 mm
Water droplets freeze in the air, smaller than 5 mm
Water droplets freeze when they hit the surface, layer is called “glaze”
Ice pellets, larger than 5 mm
Water vapor turns directly into ice crystals, 6 sided
What tools are used to measure precipitation?
o Rain gauge – rain, sleet, freezing rain
o Ruler – snow