Weather and Climate Notes Part 1

What type of weather will a LOW pressure system bring? As a low pressure system approaches the pressure will drop due to rising air. As the air rises it cools and water vapor condenses forming clouds. As the low moves away temperatures usually drop because the air is coming from the north/northwest on the back side of the low.

What type of weather will a HIGH pressure system bring? As a high pressure system approaches the pressure will rise due to sinking air. As the air sinks it does not allow clouds to form. As the high moves away temperatures usually rise because the air is coming from the south/southwest on the back side of the high.

Describe conditions associated with frontal boundaries that result in severe weather. When a cold air mass collides with a warm air mass a Cold Front forms.

The cold air mass plows under and quickly lifts the warmer, less dense air There are strong upward motions that causes vertical (tall) clouds The slope of the cold front is very steep Intense rain and thunderstorms may occur

Weather and Climate Notes Part 2

How are clouds formed by convection? Warm, moist air rises up into the atmosphere due to density differences The air cools, becomes saturated, reaching the dew point. The water vapor condenses on condensation nuclei

How are clouds formed by mountains? When moist air moves over a mountain, it is forced up into the atmosphere The air cools, becomes saturated, and reaches the dew point. Water vapor begins to condense on condensation nuclei

How are clouds formed by fronts? The cold dense air forces the warmer air up into the atmosphere The air cools, becomes saturated, reaching the dew point. The water vapor condenses on condensation nuclei

Weather and Climate Notes Part 3

Why do so many tornadoes occur in Tornado Alley? IT IS A REGION OF THE COUNTRY WHERE WARM WET AIR FROM THE GULF COLLIDES WITH DRY AIR FROM THE WEST

Do tornadoes tend to happen early in the day, or late? LATE IN THE DAY WHEN THE ATMOSPHERE HAS HAD TIME TO HEAT UP, HOWEVER THEY COULD HAPPEN ANYTIME, EVEN AT NIGHT

What is the difference between a thunderstorm and a supercell? Supercell thunderstorms are larger than thunderstoms and have a strong rotating updraft called a mesocyclone. Mesocyclone A mesocyclone is a powerful rotating updraft of warm air

How does hail form? Hail forms as rain is forced back up into the atmosphere by strong UPDRAFTS and gets LAYERED by ice until it falls back down to the surface.

Why is large hail an indication of a severe storm? If the updrafts are strong enough they will continue this process for long periods of time allowing the hail to accumulate more moisture and more moisture. Stronger storms have stronger updrafts that suspend large hail for long periods of time further adding moisture to the hail.

What do tornadoes, blizzards and thunderstorms have in common? They all form due to the interaction of the atmosphere at weather fronts

Does warm air or cold air bring storms? BOTH – IT’S WHERE THEY MEET

Weather and Climate Notes Part 4

What are the key factors needed for a hurricane to form? Warm water Coriolis Effect No wind shear (winds moving the same direction at all altitudes)

Do hurricanes and tornadoes have a season? Why? Hurricanes do have a season. They begin forming in late summer and early fall because the ocean near the equator needs time to heat up. Tornadoes do not have a season, they can happen any time of the year; but they are more common in spring and summer

What has stronger winds, a tropical storm, a hurricane, or a tropical depression? Hurricanes have 74+ mph winds Tropical storms have 39+ mph winds. Tropical depressions have winds less than 38 mph

What is the difference between the Fujita and the Saffir-Simpson scales? The Fujita scale is used to classify tornadoes based the damage they have caused; it is assigned after it has hit an area. The Safir-Simpson scale is used to classify the potential damage that a hurricane will cause when it hits land; it is assigned before it hits.

Weather and Climate Notes Part 5

What element of thunderstorms kills the most people every year? Flash Flooding kills more than 140 people each year

What form of severe weather does the most damage each year in the U.S.? Floods cause more damage than any other form of weather.

What form of hazardous weather kills the most people each year? Heat waves kill an average of 313 people every year.

Why does the United States experience some of the wildest weather on Earth? WE HAVE OCEANS ON BOTH SIDES AND CONVERGING TROPICAL AND POLAR AIR MASSES

Why do so many severe storms happen in the spring? Most severe weather takes place in the spring as cold, dry air from the north collides with warm, moist air from the south over the central US.