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Weather Compiled by Rocio Munoz

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1 Weather Compiled by Rocio Munoz
Definition:  the meteorological conditions- temperature, wind, clouds, precipitation... Compiled by Rocio Munoz

2 TEKS 8.10 A recognize that the Sun provides the energy that drives convection within the atmosphere and oceans, producing winds and ocean currents Deconstruct the TEKS Recognize Sun provides energy drives convection in the atmosphere to produce wind Recognize Sun provides energy drives convection in the ocean to produce ocean currents

3 What is Weather ?

4 Weather Weather Refers to temperature, amount of moisture, air pressure, wind direction, and wind velocity. Local weather is affected by movement of air masses into the local area.

5 Weather Factors The day to day changes in the atmosphere.
Air Pressure Temperature Wind Moisture

6 Tools to Study Weather Thermometer: instrument that measures the temperature Barometer: instrument that measures atmospheric pressure (pressure from the weight of the air) Hygrometer: instrument used to measure the relative humidity of the atmosphere (ratio of the amount of water in the air at a given temperature to the maximum it can hold at that temperature)

7 More Weather Tools In a psychrometer, one thermometer is ordinary and the other has a cloth wick over its bulb and is called a wet-bulb thermometer. When a reading is to be taken, the wick is first dipped in water. The water evaporates from the wick, cooling the wet-bulb thermometer. Then the temperatures of both thermometers are read. If the surrounding air is dry, more moisture evaporates from the wick, cooling the wet-bulb thermometer more so there is a greater difference between the temperatures of the two thermometers. If the surrounding air is holding as much moisture as possible - if the relative humidity is 100% - there is no difference between the two temperatures. Psychrometer: A special type of hygrometer with two thermometers Rain Gauge: An instrument used to measure the amount of rain that has fallen. Measurement is done in hundredths of inches (0.01"). Anemometer: An instrument used to measure wind speed

8 Under Pressure As we know, the air in the atmosphere is made up of a number of gases. These gases press down on the Earth’s surface, exerting a force that we call atmospheric pressure or air pressure. Although we are usually unaware of this pressure, it actually presses down very hard – roughly equivalent to the force of an elephant balancing on a desk! Each layer of air presses down on the layers below, and so the greatest pressure is at ground level where we have the maximum amount of air above. In the stratosphere air pressure decreases until it reaches about zero.

9 Changes in Air Pressure
Changes in air pressure are caused by the difference in air temperature above the earth.  Land masses and areas of water change the temperature of the air above them.  These changes create wind and cause pressure patterns to develop.  The wind moves these pressure patterns that change as they pass over mountains, oceans, and other areas.

10 Heat Energy and the Atmosphere
The Sun

11 The Sun’s Energy also powers the water cycle

12 Radiant energy from the sun is transformed into heat by absorption at the earth’s surface.

13 The angle of the sun’s rays affect the heating of Earth’s Surface
The uneven distribution of heat energy in the atmosphere is the cause of weather.


15 "Winds blow, from high to low!"
Changes in air pressure bring changes in the weather and make winds blow. Air usually moves from areas of high pressure to areas of low pressure, and this produces winds. This can be easily remembered with the phrase: "Winds blow, from high to low!"

16 Wind Facts: Winds move from high to low pressure areas.
High pressure is associated with cold air, low pressure with warm air. Warm air rises because it is less dense than cold air Both local and global winds are caused by differences in air pressure due to unequal heating of the air.

17 Air Circulation Pattern
, When air is heated, it becomes lighter (less dense) than the surrounding air. Therefore, warm air rises. Cool air is heavier (more dense), so it tends to sink. As air rises or falls, the surrounding air rushes in to replace it, causing air to circulate. This circulation, brings about changes in the weather. The heating of Earth's surface depends on the nature of the surface

18 Local Winds Sea Breeze, Land Breeze, and Monsoon Land Breeze Occur on warm sunny days Air over the land heats faster than the air over the cool ocean Warmer air rises Cool air flows in under it to fill the area over the land This air warms and the cycle continues Sea Breeze Occur at night and on cool days Air over water maintains an even temperature Air over land cools faster Cooler air flows from the land out under the warmer ocean air This air warms and the cycle continues

19 Global Winds

20 Coriolis Force (effect)
The original circulation of air caused by convection is in a north –south direction. But because the earth turns toward the east, all winds veer from this north-south direction. The Coriolis force is caused by the differences in velocity of rotation at different latitudes. At the equator the velocity of rotation is at its maximum (1,000 mi/hr). At the poles the velocity of rotation is at its minimum (0mi/hr). The velocity of rotation gradually decreases from the equator to the poles.

21 Rotation of the earth, distribution of land and water areas, and the exchange of heat between warm and cold areas causes the circulation patterns of the atmosphere.

22 Trade Winds or Easterlies - An area of calm found at the equator.
Major Wind Systems Trade Winds or Easterlies - An area of calm found at the equator. When warm air from the equator rises, it cools, and flows back toward the equator. It appears to flow to the west because of the Coriolis Effect. Prevailing Westerlies - When air moves toward the poles, it flows from west to east. clouds, rain , or snow may occur when highs and lows overtake one another Polar Easterlies - Air over the poles cools and sinks back down, it eventually returns to the equator.


24 The Jet Stream The Polar Front at the Tropopause
Recall that winds aloft are faster than surface winds

25 Climate Climate is the general character of the weather that prevails in an area from season to season and from year to year. It can be thought of as the average weather of an area over a long period of time. Factors that combine to produce different climates: A- latitude B- altitude C- Large bodies of water D- Mountain barriers

26 8.10 B identify how global patterns of atmospheric movement influence local weather using weather maps that show high and low pressure and fronts. Deconstruct the TEKS Identify Global patterns of atmospheric movement Influence weather Using weather maps that show H and L and fronts

27 ©Mark Place, Air Masses

28 AIR MASSES What's the definition? A large body of air with similar characteristics throughout

29 Air masses are classified based on their
and amount of temperature moisture

30 Air masses get their characteristics based on
where they form

31 The abbreviations used to classify air masses
use the following letters: c, m, T, P, and A. For each letter, describe its property: Word Means c m T P A continental dry maritime moist Tropical warm Polar cold Arctic very cold

32 What would their characteristics be?
mT cP warm and moist cold and dry

33 High or Low Pressure? mT cP H L



36 What type of air mass would form over each area? Please label. cA mP mP cP cT mT mT mT

37 World Air Mass Source Regions



40 Animation #1

41 cP air mass dry, cool air High Pressure Area mT air mass warm, moist air Low Pressure Center

42 cP air mass dry, cool air High Pressure Area mT air mass warm, moist air Low Pressure Center

43 cP air mass dry, cool air High Pressure Area mT air mass warm, moist air Low Pressure Center

44 cP air mass dry, cool air High Pressure Area mT air mass warm, moist air Low Pressure Center

45 cP air mass dry, cool air High Pressure Area mT air mass warm, moist air Low Pressure Center

46 Air Masses Facts: Air mass is a region of air with similar properties in the atmosphere Air mass typically move from the west to the east in the Northern Hemisphere under the influence of the prevailing westerlies. Example: Hot, dry air from the continental tropical air mass will bring hot, dry weather to Texas when it moves in from Arizona. Masses of air that stay in place for some length of time take on the characteristics of temperature and humidity from the surface of the earth over which the air stands. Masses of air that originate over the ocean tend to be moist There are four major types of air masses that affect the weather in the United States: Maritime Tropical Maritime Polar Continental Tropical Continental Polar

47 Characteristics Name Characteristics Maritime Tropical
Forms near the equator. Warm, moist air Summer- very hot, humid weather Winter - rain or snow Maritime Polar Forms over the Pacific Ocean in both the winter and the summer. Summer – cooler temperatures to the eastern states and fog to California and other western states. Winter- Heavy snow and very cold temperatures Continental Tropical Forms over land in Mexico. Brings dry, hot air to the southwestern states. Continental Polar Forms over land in northern Canada. Winter- very cold temperatures in the United States


49 High and Low Pressure Systems
High Pressure Areas (H) – air tends to sink, winds blow outward from the center, turning clockwise. High pressure area usually brings clear skies, dry weather, and gentle winds. Low Pressure Areas (L) – the air tends to rise, and winds spiral in toward the center in a counterclockwise direction. The low pressure areas usually brings cloudy, wet weather, often with strong, gusty winds.

50 High and Low Pressure Systems
Areas of high pressure can be caused when cool air is sinking and pressing on the ground. When warm air rises, however, it causes a region of low pressure. Regions of sinking air are called highs, high pressure regions, or anticyclones. Clear skies and fair, dry weather usually occur in these regions. Regions of rising air are called lows, low pressure regions, depressions, or cyclones. Clouds, rain, and strong winds often occur in these regions.

51 High vs. Low High pressure areas are generally larger and move slower than low pressure. The winds are generally weaker than those around a low pressure, especially in the center. High pressure does not necessarily mean warm weather, a 'cold anticyclone' has cold air near the ground. These cold anticyclones are common in Siberia and Canada.

52 If cold air is moving toward warm air, then it is a “cold front”.
Definition: a warm-cold air boundary with the colder air replacing the warmer. A typical cold front plows into warmer, lighter air forming towering clouds, rain, and often thunderstorms.

53 Air Movement- Cold Front

54 Symbol for Cold Front The weather map symbol for a cold front is a blue line with triangles pointing the direction the cold air is moving. As a cold front moves into an area, the heavier, cool air pushes under the lighter, warm air it's replacing. The warm air cools as it rises. If the rising air is humid enough, water vapor in it will condense into clouds and maybe precipitation.

55 Weather Associated with Cold Fronts
In the summer, an arriving cold front can trigger thunderstorms- sometimes severe with large hail, dangerous winds, and even tornadoes!

56 Warm Front If warm air is moving toward cold air, it is a “warm front”. Definition: boundary where a warm air mass replaces a cool air mass. Warmer tropical air is forced over the cooler polar air. Heavier, denser cold air retreats slowly as warm air rises over cold air, bringing widespread clouds and precipitation.

57 Air Movement- Warm Front

58 Symbol for Warm Front The weather map symbol for a warm front is a red line with half-circles on it. The circles on the red line point in the direction the warm air is moving. As the warm air advances northward it rides over the cold air ahead of it, which is heavier. Sometimes the cold air slows the warm front down and can lead to several days of wet weather.

59 Weather Associated with Warm Fronts
When a warm front passes through, the air becomes noticeably warmer and more humid than it was before. As the warm air rises over the cold air the water vapor in it condenses into clouds that can produce rain, snow, or sleet. A slow-moving warm front can mean hours, if not days, of cloudy, wet weather before the warm air finally arrives.

60 Stationary Front When a warm or cold front stops moving, it becomes a stationary front. Once this boundary resumes its forward motion, it once again becomes a warm front or cold front. A stationary front is represented by alternating blue and red lines with blue triangles pointing towards the warmer air and red semicircles pointing towards the colder air.

61 Occluded Front When a cold and warm front merge into one front, it is known as an occluded front, or occlusion. The warm air mass becomes trapped between two colder air masses, one from the west and one from the east, and is forced up. Occluded means "closed in." A large area of bad weather accompanies the occluded front. Warm front weather will be followed by cold front weather in all occlusions.

62 Which types of fronts can you find on this map?

63 Predicting the Weather
Weather forecasting takes time and research. Here are just a few tips on scientific weather forecasting … Watch for a steadily falling barometer with winds from the east/northeast.  This usually indicates the arrival of a storm from the south or southwest within 24 hours. Expect fair weather if the barometric pressure is steady and winds are coming from the southwest to northwest. Look for the presence of cirrocumulus clouds that are in patches or in widespread layers. This is usually a sign of an advancing, large, unstable weather system. Watch for the formation of cumulonimbus clouds early in the day. As they become more active, the likelihood of severe weather increases. Expect nice weather the following day if the night sky is clear.

64 Weather Maps Blue book page 71

65 TEKS 8.10 A recognize that the Sun provides the energy that drives convection within the atmosphere and oceans, producing winds and ocean currents. 8.10 C Identify the role of the oceans in the formation of weather systems such as hurricanes Deconstruct the TEKS 8.10 C Identify Role of the oceans Formation of weather systems Hurricanes

66 Ocean Currents The patterns of ocean surface currents are determined by the force and direction of the winds and by land masses that act as barriers.

67 Ocean Currents Surface currents are cause by winds, and they have circulation similar to those in the atmosphere. For example, surface currents in the tropics are set in motion by the trade winds that drive the ocean water before them. Density Currents formed by the movement of more dense seawater toward an area of less dense seawater. Temperature and salinity affect the density of seawater. Ocean currents traveling away from the equator are warm-water currents Ocean currents traveling toward the equator are cold- water currents.

68 Ocean Currents Examples of warm currents: Examples of cold currents:
Gulf Stream Alaska Brazil Norwegian Agulhas Mozambique Kuroshio (Japan current) East Australia Examples of cold currents: California current Peru current Canary East Greenland Labrador Benguela West Australia Oyashio

69 How Do Hurricanes Form? Hurricanes need four conditions to form:
low air pressure warm temperatures moist ocean air tropics winds (near the equator). It starts as a tropical wave, a westward-moving area of low air pressure. As the warm, moist air over the ocean rises cold air from above replaces it producing strong gusty winds, heavy rain, and thunderclouds (tropical disturbance). As the air pressure drops and there are winds up to 38 mph, it is a tropical depression. When the cyclonic winds speeds from 39 to 73 mph, it is a tropical storm. The storm becomes a hurricane when there are winds of 73 mph or more.

70 Hurricane Safety If a hurricane watch is issued:
Listen to a battery-operated radio or television Check emergency supplies and fuel your car Bring in outdoor objects and anchor objects that cannot be brought inside. Secure buildings by closing and boarding up windows Store drinking water Review evacuation plan If at home, stay inside, away from windows, skylights, and glass doors.

71 El Nino Weather La Nina Weather El Nino and La Nina
What are El Nino and La Nina? El Nino - (El Nee-nyo) is the warming of water in the Pacific Ocean. La Nina - (Lah Nee-Nyah) is the cooling of water in the Pacific Ocean. El Nino Weather La Nina Weather Rain and flooding along the Pacific coast Warm water disrupts food chain of fish, birds, and sea mammals Tornadoes and thunderstorms in southern US Fewer than normal hurricanes in the Atlantic Snow and rain on the west coast Unusually cold weather in Alaska Unusually warm weather in the rest of the USA Drought in the southwest Higher than normal number of hurricanes in the Atlantic

72 Bibliography Front. [Online image] Available August 2004. Cold Front. [Online image] Available August 2004. Warm Front. [Online image] Available August 2004. Cold and Warm Front Animation. [Online image] Available August 2004. Air Masses. [Online image] Available August 2004. Satellite Image of Cold Front. [Online image] Available August 2004. Thunderstorm. [Online image] Available August 2004. Tornado. [Online image] Available August 2004. Weather Cartoon. [Online image] Available August 2004. Walking in the Rain. [Online image] Available August 2004. Thermometer. [Online image] Available August 2004. Barometer. [Online image] Available August 2004. Hygrometer. [Online image] Available August 2004. Rain Gauge Detailed. [Online image] Available August 2004. Psychrometer. [Online image] Available August 2004. Substitute Weatherman. [Online image] Available August 2004.

73 Weather Unit

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