6th Grade Chapter 18 Part 2

Weather & climateWeather & climate

Chapter 18 part 2Chapter 18 part 2

Weather Factors Weather Factors H.W. pg. 461 1-4H.W. pg. 461 1-4

Weather refers to the state of the Weather refers to the state of the atmosphere at a specific time and placeatmosphere at a specific time and place

One weather factor is air temperature. One weather factor is air temperature. Temperature is a measure of the average Temperature is a measure of the average amount of motion of moleculesamount of motion of molecules

When the temperature is high, molecules When the temperature is high, molecules in the air move faster and they feel in the air move faster and they feel warmer.warmer.

Weather factorsWeather factors

Wind- air moving in a specific direction is called Wind- air moving in a specific direction is called wind.wind.

Wind results because air moves from high Wind results because air moves from high pressure systems (cold air) to low pressure pressure systems (cold air) to low pressure systems (warm air).systems (warm air).

Wind is measured using a wind vaneWind is measured using a wind vane

Dew point- temperature at which air is saturated Dew point- temperature at which air is saturated and condensation forms is the dew point. This and condensation forms is the dew point. This changes the amount of water vapor in the air.changes the amount of water vapor in the air.

Weather factorsWeather factors

Humidity- the amount of water vapor in the air is Humidity- the amount of water vapor in the air is called humidity, and is evaporated water called humidity, and is evaporated water molecules.molecules.In cooler temperatures, water molecules stick In cooler temperatures, water molecules stick together to form rain. In warmer weather, they together to form rain. In warmer weather, they move so fast, that they don’t get a chance to move so fast, that they don’t get a chance to stick together.stick together.Relative humidity is the amount of water vapor Relative humidity is the amount of water vapor present in the air compared to the amount present in the air compared to the amount needed for saturation at a specific temperatureneeded for saturation at a specific temperature

Cloud FormationCloud Formation

Clouds are classified by shape and height. Clouds are classified by shape and height. Stratus clouds- form layers or sheets of clouds in Stratus clouds- form layers or sheets of clouds in the sky at low altitudes. Fog is an example of a the sky at low altitudes. Fog is an example of a stratus cloud.stratus cloud.Cumulus clouds- massive, puffy, white clouds Cumulus clouds- massive, puffy, white clouds with flat bases. They have great altitudes.with flat bases. They have great altitudes.Cirrus clouds- they appear fibrous or curly. They Cirrus clouds- they appear fibrous or curly. They are thin, white and made of ice crystals and they are thin, white and made of ice crystals and they can indicate an approaching storm.can indicate an approaching storm.Nimbus clouds- these are clouds associated with Nimbus clouds- these are clouds associated with snow. These clouds go up to 18km high.snow. These clouds go up to 18km high.

Stratus CloudStratus Cloud

Cumulus CloudCumulus Cloud

Cirrus CloudCirrus Cloud

Weather PatternsWeather Patterns

Changes in weather are due to movements of air Changes in weather are due to movements of air masses, which are large bodies of air that masses, which are large bodies of air that contain properties of the surface they developed contain properties of the surface they developed over. over. Air masses over desserts will have less moisture Air masses over desserts will have less moisture than an air mass that forms over water.than an air mass that forms over water.The boundary between two air masses of The boundary between two air masses of different moisture, temperature is called a front.different moisture, temperature is called a front.A cold front is shown with a blue line with A cold front is shown with a blue line with triangles. The cold air wedges under warmer air triangles. The cold air wedges under warmer air like a plow. That warm air is cooled, and the like a plow. That warm air is cooled, and the water vapor forms clouds.water vapor forms clouds.

Weather PatternsWeather Patterns

Warm fronts are shown with a red line with semi-Warm fronts are shown with a red line with semi-circles. They form when lighter, warm air goes circles. They form when lighter, warm air goes over colder air.over colder air.Thunderstorms or hail occur in warm moist air Thunderstorms or hail occur in warm moist air masses, when warm air is forced upward by cool masses, when warm air is forced upward by cool air.air.When the cold air lifts up the warm air, it causes When the cold air lifts up the warm air, it causes parts of a cloud to become oppositely charged parts of a cloud to become oppositely charged creating lightning.creating lightning.Thunder is the rapid heating of air around a bolt Thunder is the rapid heating of air around a bolt of lightning.of lightning.

Severe WeatherSevere Weather

Tornado- a violent rotating column of air in Tornado- a violent rotating column of air in contact with the ground. They are due to severe contact with the ground. They are due to severe storms that cause strong winds to blow in storms that cause strong winds to blow in different directions. These winds cause the different directions. These winds cause the column to form.column to form.Hurricanes- large swirling, low pressure system Hurricanes- large swirling, low pressure system that forms over warm Atlantic and Pacific Ocean that forms over warm Atlantic and Pacific Ocean water. A hurricane must have winds of at least water. A hurricane must have winds of at least 119km-hr.119km-hr.H.W. pg 478, 1-15H.W. pg 478, 1-15

Katrina Katrina

Weather ForecastsWeather Forecasts

Meteorologist- a person who studies weather. Meteorologist- a person who studies weather. They use a map called a station model.They use a map called a station model.This model shows weather conditions over This model shows weather conditions over specific locations on Earths surface. Weather specific locations on Earths surface. Weather maps have isotherms, which are lines that maps have isotherms, which are lines that connect points of equal temperature and isobars connect points of equal temperature and isobars which connect points of equal atmospheric which connect points of equal atmospheric pressure.pressure.Isobars can also indicate wind speed and the Isobars can also indicate wind speed and the movement of high and low pressure systems.movement of high and low pressure systems.H.W. pg 480, 1-20H.W. pg 480, 1-20

ClimateClimateClimate is a pattern of weather that occurs in an Climate is a pattern of weather that occurs in an area over many years(30). It helps determine area over many years(30). It helps determine plant and animal types that live in a certain area. plant and animal types that live in a certain area.

The tropics is the region between latitude 23.5N The tropics is the region between latitude 23.5N and 23.5S. They receive the most solar radiation and 23.5S. They receive the most solar radiation because the sun shines directly over them. because the sun shines directly over them. That’s why the tropics have such hot That’s why the tropics have such hot temperatures.temperatures.

The polar zones extend from 66.5 N and 66.5 S The polar zones extend from 66.5 N and 66.5 S latitude.latitude.

Between the tropics and polar zones are Between the tropics and polar zones are temperature zones that have moderate temps.temperature zones that have moderate temps.

Climate changesClimate changes

The seasons are short periods of climatic The seasons are short periods of climatic change caused by changes in the amount of change caused by changes in the amount of solar radiation an area receives.solar radiation an area receives.Throughout the year, Earth receives different Throughout the year, Earth receives different amounts of radiation because the Earth is tilted.amounts of radiation because the Earth is tilted.Tropic areas do not have much seasonal Tropic areas do not have much seasonal temperature change but do have dry and rainy temperature change but do have dry and rainy seasons.seasons.Temperature zones have warm summers, cool Temperature zones have warm summers, cool winters, and mild spring and falls. winters, and mild spring and falls.

Climate ChangeClimate Change

Climates can change due to atmospheric solids Climates can change due to atmospheric solids and liquids, like soil particles, automobile and liquids, like soil particles, automobile exhausts, and smoke stack emissions.exhausts, and smoke stack emissions.These particles block solar radiation and cool These particles block solar radiation and cool the planet. the planet. Earths movements also affect climate. About Earths movements also affect climate. About every 41,000 years, the tilt of the earth changes every 41,000 years, the tilt of the earth changes +- 3 degrees. This can make summers hotter in +- 3 degrees. This can make summers hotter in some places and winters cooler in other places some places and winters cooler in other places because it changes the amount of radiation because it changes the amount of radiation absorbed in certain areas. absorbed in certain areas.

Climate ChangesClimate Changes

Plate movement of the crust causes changes by Plate movement of the crust causes changes by affecting the transfer of heat on Earth which affecting the transfer of heat on Earth which affects wind and precipitation patterns. affects wind and precipitation patterns.

The Greenhouse Effect is a natural heating The Greenhouse Effect is a natural heating process that occurs when certain gases in process that occurs when certain gases in Earth’s atmosphere trap heat. This keeps the Earth’s atmosphere trap heat. This keeps the Earth warmer than what it otherwise would be. Earth warmer than what it otherwise would be. The gases include water vapor, CO2 and The gases include water vapor, CO2 and methane gas. Without them, life would not be methane gas. Without them, life would not be possible on Earth.possible on Earth.

Global WarmingGlobal Warming

Global warming is the increase in average global Global warming is the increase in average global surface temperature. Over the past hundred surface temperature. Over the past hundred years, the average global surface temperature years, the average global surface temperature has increased 0.6 degrees Celsius. has increased 0.6 degrees Celsius. This increase could cause glaciers to melt and This increase could cause glaciers to melt and sea levels to rise.sea levels to rise.Global warming also increases the CO2 levels in Global warming also increases the CO2 levels in our air which could increase the average surface our air which could increase the average surface temperature of the Earth.temperature of the Earth.H.W. pg 508, ques. 1-15.H.W. pg 508, ques. 1-15.