Weather

What is difference between weather and climate?

What are four factors that influence the climate of a region? Describe each factor.

Climatologists categorize the earth’s climates into zones that are mostly based on average temperatures and amount of precipitation.  What is the main cause for the climate of a particular region---in other words, what is the reason for the average temperature and the amount of participation in a particular region?

The earth has five layers of atmosphere.  We live and breathe in the layer called the troposphere. Weather happens in the troposphere.  Describe the key elements of this layer that we live in.

The water cycle and weather go hand-in-hand.  Explain the water cycle in terms of weather.

When the air is cold, the water vapor in clouds turns into tiny crystals of ice.  These crystals bond together to make snowflakes.  How does water vapor get into clouds to begin with?

At any given time, about half the sky all over the world is covered with clouds.   How do clouds form?

Why do clouds usually look white or gray?

Density is a measure of the amount of matter in a given space.  If you take a soft slice of bread and squeeze it into a ball, you are increasing its density. Air molecules can also be squeezed together because of the weight of the air above them.  This means that air is denser lower in the atmosphere than at higher altitudes.  Heat can also make air less dense.  When air is less dense, it is less heavy. Warmer air has lower air pressure, and colder air has higher air pressure.  Density differences between warm and cool air cause air movement or wind. Explain in detail why cold air is denser and heavier than warm air. (It’s all about the molecules).

What is the relationship between the oceans and weather?

The Gulf Stream is a powerful, fast-flowing, warm ocean current. Use the National Weather Service’s ocean current map to view worldwide currents.  In what part of the world does the Gulf Stream flow? How does it affect weather and climate?

Ocean currents play a huge role in global climates.  What is the “ultimate reason” for the earth’s ocean currents?  How do the currents affect climate?

Trace the movement of a drop of water as it evaporates from the ocean and then eventually returns.  This is the water cycle, and it is driven by the heat of the sun and is part of the weather patterns of the earth.

Oceans cover 71% of the surface of the earth, and they have a huge effect on our weather.  Explain how the earth’s oceans and the earth’s weather are intertwined.

Air pressure is the weight of earth’s atmosphere pressing down on everything below it. What is the relationship between air pressure and wind?

Where does the energy that drives the wind come from?

How do temperature differences make the wind blow?  (Remember that the sun does not heat the earth evenly).

Winds help distribute the sun’s warmth.  What are other useful aspects of wind?  

The Jet Stream is a strong global wind that blows from west to east around the world.  There are two jet streams in the northern hemisphere and two in the southern hemisphere.  What causes the Jet Stream?

How does the jet stream influence the earth’s weather?

Wind is simply moving air.  The wind blows because air moves from areas of high pressure to areas of low pressure.  The bigger the difference in pressure between the two areas, the faster the wind blows. What causes differences in air pressure?

Global winds influence weather and climate because they tend to blow in the same direction across the same parts of the world fairly constantly.  They move warm air out of the area around the equator and cold air out of polar regions. They influence ocean currents. The trade winds are constant winds that blow towards the equator.  Because they blow mainly in one direction, they are also part of the groups of winds called prevailing winds. How did the trade winds get their name?

Utah’s weather is sometimes influenced by special winds called chinook winds.  Using the great resources at Utah’s Online Library, find out what chinook winds are.

Uneven heating of the surface of the earth by the sun creates high and low pressure areas. How do high and low pressure systems affect weather?

What are air masses?

Why does local weather change when a front passes by?

What is the relationship between landforms and global climate and weather? For example, when air currents bump into a mountain slope, the air is forced upwards.  As it travels higher, the temperature drops and clouds form.  It is very common to see clouds above mountains, and it often rains and snows more in mountain environments.

Why is there a greater fluctuation in daytime and nighttime temperatures on land as opposed to the ocean?  This fluctuation influences the weather in cities close to the ocean and cities far from the ocean.  It is why San Diego has a fairly constant temperature, and Utah can have cool nights even in the summer.

Uneven Heating of the Earth’s Surface Chart
Some areas of the earth receive more heat from the sun than other areas. This is the reason for weather and climate. Using the great resources at Utah’s Online Library, learn more about this uneven heating.

Factor that causes uneven heating	How it causes uneven heating
Seasons (tilt of the earth and latitude)
Shape of the earth
Earth’s rotation which results in daytime and nighttime
Earth’s surface (land masses and oceans)

In studying climate, NASA refers to the "great ocean conveyor belt" which describes the major ocean currents that move warm water from the equator to the far northern and southern part of the earth (the poles) and cold water from the poles back toward the equator. Explain how this happens.  Remember that the sun is the source of all weather. Use some of the resources at Utah’s Online Library to further research how ocean currents affect the world’s climates.

In Utah, it’s usually cold in the winter and warm in the summer.  We also have different weather conditions in spring and fall.  Explain why we have seasons with different kinds of weather.

The National Weather Service defines precipitation as ”any form of water particle, whether liquid or solid, that falls from the atmosphere and reaches the ground.”  It lists eight different types of precipitation.  Choose one of the precipitation types that you have personally witnessed and describe your experience.  Obscurations are atmospheric occurrences that are not precipitation.  The NWS also lists seven different types of obscurations.  Choose one that you have personally witnessed and describe your experience.

Why does it rain?

Snow is made up of tiny ice crystals.   When air temperatures are very cold, the water droplets in the clouds freeze to make tiny ice crystals.  As the crystals fall through cold air, they combine and form snowflakes. Utah is famous for its powdery snow that skiers love.  What makes some snow powdery?

How do snowflakes form?

You may have heard Utah weathercasters talk about lake effect snow that parts of Utah receive because of their proximity to the Great Salt Lake.  What is lake effect snow?

Thunderstorms get their name from the thunder and lightning that they produce.  They are common storms that usually produce a large quantity of rain. This map shows the average number of thunderstorms that occur throughout the United States.  Look at the color sections on the map and then check for the number at the top of the map that corresponds to that color.  Utah has two different areas that receive different quantities of thunderstorms each year.  How many thunderstorms occur where you live in Utah?  What part of the U.S. has the most thunderstorms?

Lightning is caused by electricity flowing between negatively charged clouds and positively charged objects on the ground. Why does lightning strike in a jagged line instead of a straight line?  We usually see lightning going from cloud to ground.  In what other direction can it travel?

Lightning is a very common weather occurrence. About how many cloud to ground lightning strikes happen in the United States each year?

What causes thunder?

How do tornadoes form?

In most years, about 1200 tornadoes occur in the United States. On average, how many tornadoes occur each year in Utah?  Which states have the most tornadoes?

What is Tornado Alley?  In terms of air masses and weather fronts and physical geography why does this alley exist?  Where is it located?

Some areas in Utah occasionally form a waterspout.  What is a waterspout?

How do hurricanes form?

Hurricanes (also called tropical cyclones) often hit the Gulf Coast of the United States (Texas, Louisiana, Florida, etc.), the Caribbean islands (Bahamas, Haiti, Cuba, etc.), Central America (Guatemala, Honduras, Costa Rica, etc.), and even Japan.  What do these countries have in common that make them prone to hurricanes?

What are five ingredients that are needed in order to form a hurricane?  Once the ingredients are in place, how do hurricanes form?

Hurricanes and cyclones start in the oceans near the equator.  Why do hurricanes and cyclones need the particular water around the equator in order to form?  Relate this back to the role that the sun plays in the creation of weather.

We might have heard about heavy monsoon rains.  But what actually is a monsoon?  What causes monsoon seasons? In what areas of the world do monsoons mostly occur?

All weather on earth is caused by the sun.  The sun is also the reason for the northern lights and southern lights, also called the auroras.  Explain how the auroras work.

How do rainbows form?

Sometimes when you go outside in the morning, the ground is damp with moisture. This is dew.  How does dew form?  (It’s all about the water cycle.)

How does hail form?  Which states have the most storms that produce hail?

The weather phenomenon called El Nino is all about ocean water temperature.  Explain how El Nino works.  Be sure and include the effects of this weather system.  How often does El Nino occur?

What is the difference between El Nino and La Nina?

Droughts are periods of time when very little rain falls.  What are some factors that contribute to droughts?

What are some of the weather trends that cause drought?

The greenhouse effect is a natural process that warms the planet and is essential to life on earth.  What are some of the most common greenhouse gases?

Sunlight passes through the atmosphere, but a portion of the heat bounces back into space.  Gases like carbon dioxide trap the heat from the sun and hold on to it.  This helps control earth’s temperature, and this natural greenhouse effect is beneficial to the planet.  However, when extra carbon dioxide is released into the atmosphere, it traps more heat than usual and magnifies the greenhouse effect that warms the oceans and land masses.  What are some of the human activities that cause this extra carbon dioxide to release into the atmosphere?

If the atmosphere had too few greenhouses gases what would happen to the earth’s climates?  If the atmosphere has too many greenhouse gases such as carbon dioxide, what could happen to the earth’s climates?

Because of the beneficial nature of the greenhouse effect, the average surface temperature of the earth is about 59 degrees Fahrenheit.  This average temperature creates climates that are perfect for life to exist. Without the natural greenhouse effect, what would the average temperature on earth be? There are 5 layers to earth’s atmosphere.  The troposphere is the closest layer to the earth.  The next layer is the stratosphere.  Within the stratosphere is a protective layer of ozone.  This ozone layer (ozone is a type of oxygen molecule) is important because it can absorb much of the harmful ultraviolet (UV) light from the sun so that it doesn’t reach the ground.  The ozone layer has been thinning.  What are some of the things that scientists think are causing the thinning of the ozone layer?  What kind of harm does UV light do to living things?  In what part of the world is the ozone layer the most thin? What steps have been taken to prevent further ozone layer thinning?