Weather & Climate Mon-Tues 3/30-31
Take a look at climate on page 484 in your textbook Quiz review Take out your homework Popcorn reading Discussion Wrap up facts
HW: Take out your agenda Homework: Re-read chapter 17 section 1 &3. Answer these What determines climate? How does latitude, oceans, and other factors affect the climate of a region? What are causes of climate change?
SPOBGE 3/31/15 1. Why does a sea breeze occur during the day? 2. Why does a land breeze occur during the night?
Answers 1. When the Sun is out (day), the land gets warmer quicker than water. Because of convection currents, warm air rises from the land and is replaced by cooler air from the ocean/sea. A cool breeze moves onto the land. 2. When it is night, happens the land becomes cool quicker than water. Because of convection currents, warm air rises from the water and is replaced by cooler air from the land. A cool dry breeze moves out to the ocean.
Air Masses & Fronts Use your handout to fill in the blanks
Air Mass A huge body of air that has similar temperature, humidity (amount of moisture), and air pressure
Types of Air Masses Maritime Tropical Warm, humid air masses form over oceans near the tropics In summer, brings hot humid weather In winter brings heavy rain or snow Maritime means from nearby sea or ocean.
Types of Air Masses cont d Maritime Polar Cool, humid air masses from over the icy cold North Pacific and North Atlantic oceans In summer, cool humid air often brings fog, rain, & cool temperatures
Types of Air Masses cont d Continental Tropical Hot dry air masses form only in summer over dry areas over the southwest and northern Mexico
Types of Air Masses cont d Continental Polar Large continental polar air masses form over central & northern Canada & Alaska Bring cold, dry air Winter clear, cold, dry air Summer storms may occur when continental polar air masses move south & meet maritime tropical air masses moving north Continental means it comes from off the land (little to no moisture)
How Air Masses Move In Northern Hemisphere, the Prevailing Westerlies move masses from West to East - This is why most of our weather travels from the west to east.
Global winds (Write this in any space provided) Are large wind patterns that occur in different areas on Earth (latitudinal lines) and are caused by the exchange of warm and cold air that occurs between the equator and the poles. This exchange creates very large convection currents across the globe. Global winds push air masses around Earth CHECK OUT WHERE WE LIVE!!!
Fronts Area where air masses meet and do not mix becomes a front - Have different temperatures and densities. Creates changeable weather and storms
Types of Fronts The kind of front that develops depends on the characteristics of the air masses and how they are moving
Cold Fronts Cold air is dense and tends to sink (high pressure) Warm air is less dense and tends to rise (low pressure) When a rapidly/fast moving cold air mass runs into a slowly moving warm air mass, the denser cold air slides under the lighter warm air
Cold Fronts cont d The warm air will cool and condense (form clouds). Lots of water means heavy rain or snow Little water means cloudy skies Move quickly causing abrupt (sudden) weather changes
Warm Fronts Moving warm air collides with slowly moving cold air Warm air moves over cold air If warm air is humid (damp), showers & light rain fall where the air masses meet If warm air is dry, scattered clouds form where they meet
Warm Fronts cont d Weather may last several days (because of slow moving mass of air) Weather is warm and humid after front passes In winter warm fronts bring
Comparing Warm and Cold Fronts Cold fronts move faster than warm fronts. The weather activity in a cold front is often violent and happens directly at the front. Cold fronts have sudden gusty winds high in the air creating turbulence (irregular motion/violent). The weather activity in a warm front generally happens before the front passes through an area. Steady rain or drizzle may fall for a long period of time. In a warm front the cloud formation is very low often creating situations of poor visibility.
Stationary Fronts Neither the cold or warm air mass has enough force to move the other Where masses meet, clouds form to make rain, snow, or fog Stationary fronts can cause many days of dreary weather.
https://www.youtube.com/wa tch?v=tkk4_f0vkhm
http://www.phschool.com/atschool/phsc iexp/active_art/weather_fronts/ Occluded (cut off) Fronts Warm air mass caught between two cold air masses The denser cool air masses move underneath the warm air mass and is pushed upward Ground temperature cools Weather may turn cloudy and rainy or snowy
Cyclones & Anticyclones (not a tornado) Cyclones Swirling center of low air pressure Cyclones and decreasing air pressure are associated with storms and precipitation Anticyclones High pressure centers of dry air (wind spiral outward from center) Causes dry, clear weather
Anticyclone Cyclone
high pressure= cold/sinking air low pressure = warm/rising air The slightly inward moving air in low pressure causes air to come together and become heated by the surface; the air is forced upward, leading to condensation and precipitation. The opposite occurs with high pressure. Air is moving away from the high pressure/cold center. As air from the surface is heated and rises, air from above must sink to take its place
What Causes Climate?
Climate Average, year-after-year conditions of temperature, precipitation, winds, and clouds in an area
Factors of Climate Temperature (tilt of Earth) Precipitation (amount of moisture in clouds)
Factors of Temperature Latitude Altitude (distance upward) Distance from large bodies of water (sea and land breeze) Ocean currents
Factors of Precipitation Prevailing winds Presences of mountains (can cause area behind mountain to become dry and warm)
Seasons Seasons are the result of the tilt of Earth s axis
Wednesday- Friday BrainPop- Tornado vs. Hurricanes Read textbook Begin Storm brochure; use textbook, brainpop, and articles to assist you.
SEVERE WEATHER
What is a thunderstorm? - A thunderstorm is a weather event where there is heavy rain, lightning, thunder roars, and possible hail. How do they form? -They occur in warm moist air masses and along fronts. -The air is forced upward where it is, cooled and condensation occurs forming clouds. cumulonimbus -Then precipitation happens in the form of rain or hail. The rain cooled air sinks and strong updrafts of warmer air causes strong winds.
Can thunderstorms cause damage? YES! How? By flooding Hail damage Wind damage Lightning strikes
What is lightning? Lightning is a bright flash of electricity produced by a thunderstorm. All thunderstorms produce lightning and are very dangerous. If you hear the sound of thunder, then you are in danger from lightning. Lightning kills and injures more people each year than hurricanes or tornadoes; between 75 to 100 people.
What causes lightning? Lightning is an electric current. In a thundercloud, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All the collisions create an electric charge. Once the cloud fills, with electrical charges, the positive charges form at the top of the cloud and the negative charges form at the bottom of the cloud. Since opposites attract, this causes a positive charge to build up on the ground beneath the cloud. The grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and - zap - lightning strikes! Lightning can also also forms within or and between between clouds, clouds. not just from the cloud to the ground
What causes thunder? Thunder is caused by lightning. When a lightning bolt travels from the cloud to the ground it actually opens up a little hole in the air, called a channel. The lightning heats up the air and causes it to expand. Once the lightning is gone the air collapses back due to quick cooling, and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound! Which do you think is hotter, a bolt of lightning, or the surface of the sun? Lightning- it is 30,000 degrees Celsius. That s 5 times hotter than the sun!!
How do tornadoes form? When thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere; this is wind shear. Rising air from the updraft of a thunderstorm tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.
Know the Lingo TORNADO WATCH - Tornadoes are possible in your area. Stay tuned to the radio or television news. TORNADO WARNING - A tornado is either on the ground or has been detected by Doppler radar. Seek shelter immediately! The Fujita Scale F0 gale tornado 40-72 mph F1 moderate tornado 73-112 mph F2 significant tornado 113-157 mph F3 severe tornado 158-206 mph F4 devastating tornado 207-260 mph F5 incredible tornado 261-318 mph Measuring Tornadoes Some damage to chimneys; breaks branches off trees; pushes over shallowrooted trees; damages sign boards. Lower limit is the beginning of hurricane-force winds. Peels surface off roofs; mobile homes pushed over; moving autos pushed off roads. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over, large trees snapped or uprooted; light-object missiles generated. Severe damage. Roofs and some walls torn off well-constructed homes; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown. Well-constructed homes leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated. Phenomenal damage. Strong frame homes disintegrate or lifted off foundations and carried considerable distance; trees debarked.
Where are tornadoes most likely to occur? The geography of the central part of the United States, known as the Great Plains, is suited to bring all of the ingredients together to forms tornadoes. This includes Texas, Kansas, and Oklahoma. More than 500 tornadoes typically occur in this area every year and is why it is commonly known as "Tornado Alley".
What is a hurricane? A hurricane is a huge storm! It can be up to 600 miles across and have strong winds spiraling inward and upward at speeds of 75 to 200 mph. Hurricanes usually lasts for over a week, moving 10-20 mph over the open ocean. Hurricanes gather heat and energy through contact with warm ocean waters. Evaporation from the seawater increases their power. Hurricanes rotate in a counter-clockwise direction around an "eye." The center of the storm or "eye" is the calmest part. It has only light winds and fair weather. When they come onto land, the heavy rain, strong winds and large waves can damage buildings, trees and cars. Similar storms are called typhoons in the Pacific Ocean and cyclones in the Indian Ocean.
How do hurricanes form? Hurricanes form over warm ocean water of 80 F or warmer. The atmosphere must cool off very quickly the higher you go. The wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface. Winds flow outward above the storm allowing the air below to rise. Hurricanes typically form between 5 to 15 degrees latitude north and south of the equator. The Coriolis effect is needed to create the spin in the hurricane.
Saffir-Simpson Hurricane Scale Category Winds (MPH) Storm Surge (Feet) Damage 1 74-95 4'-5' Minimal 2 96-110 6'-8' Moderate 3 111-130 9'-12' Extensive 4 131-155 13'-18' Extreme 5 >155 >18' Catastrophic
Can Hurricanes cause damage? Absolutely! Storm surges usually cause the most damage and death Winds can destroy homes and uproot trees Extensive rain can also cause major flooding
What is a storm surge? Shallow-Water Coastline Deep-Water Coastline
Know the Lingo TROPICAL STORM WATCH - Tropical Storm conditions with sustained winds from 39-74 mph are possible in your area within the next 36 hours. TROPICAL STORM WARNING - Tropical Storm conditions are expected in your area within the next 24 hours. HURRICANE WATCH - Hurricane conditions with sustained winds of 74 mph or greater are possible in your area within the next 36 hours. This WATCH should trigger your family's disaster plan, and protective measures should be initiated. Especially, those actions that require extra time such as securing a boat and leaving a barrier island. HURRICANE WARNING - Hurricane conditions are expected in your area within 24 hours. Once this WARNING has been issued, your family should be in the process of completing protective actions and deciding the safest location to be during the storm