More air pressure at Earth’s surface. Warm air is less dense & rises.   Air Pressure & Density More air pressure at Earth’s surface.   Warm air is less dense & rises. Cold air is more dense & sinks.

Convection Currents!

Unequal Heating Air always moves from high pressure to low pressure. Warm air rises and creates a low pressure system. Cold air sinks and creates a high pressure system.

Unequal Heating of Earth: Land vs. Water   Unequal Heating of Earth: Land vs. Water * Land and water heat up and cool down at different rates because they absorb different amounts of solar radiation. * Oceans will take a longer time to cool down in winter, making coastal areas warmer than usual.

Heating and Cooling of Land and Water Mystery…Can You Help Solve It?

The Teacher Has Performed An Experiment and Asks That YOU Help Make Some Conclusions About the Data or Information Gathered.

Experiment Materials and Procedures: The Teacher Used A Thermometer, A Heat Lamp, A Cup of Sand, and A Cup of Water to Find the Temperatures of Both the Sand and The Water Over Two Hours.

DATA FROM THE EXPERIMENT TEMPERATURES OF THE SAND The First Hour It Was Heating Up & The Second Hour It Was Cooling Down 15 Minutes 30 Minutes 45 Minutes 1 Hour 68 Degrees 74 Degrees 88 Degrees 93 Degrees 76 Degrees TEMPERATURES OF THE WATER 71 Degrees 83 Degrees 89 Degrees 87 Degrees 81 Degrees 77 Degrees 73 Degrees

Unequal Heating What heats up quicker? What heats up slower? At night, which cools down quicker? Which cool down slower?

CONCLUSION Land Heats Up And Cools Down Faster Than Water! During the day, land heats faster than a body of water, so the air above the land becomes warmer. The warm air expands and creates a low-pressure system. The cooler air above the body of water blows inland and under the warm air. At night, the opposite happens.

Unequal Heating Land heats up quickly. Land cools down quickly. Water heats up slowly. Water cools down slowly.

Global and Local Winds

Winds

Why does Air Move ? The movement of air caused by differences in air pressure is called Wind Air moves from areas of higher pressure to areas of lower pressure Differences in air pressure is caused by unequal heating of the earth *the SUN is the major source of energy for heating that generates winds Air at the equator is warmer and less dense so it rises creating an area of low pressure At the poles, the air is colder and more dense so it sinks creating areas of high pressure This cold polar air then flows towards the equator

What causes winds? Lots of difference Differences in air pressure More of a difference in pressure = faster winds Lots of difference

Local Winds Local Winds generally move short distances and can blow from any direction; caused by unequal heating of Earth’s surface within a small area They are affected by the geographical features of an area, which can produce temperature differences that cause local winds Types: Sea breeze & land Breeze Mountain breeze & valley breeze

Why is the ocean colder than the land during the day and warmer than the land during the night?

Sea Breeze (Morning) Land heats up faster than water. Hot air over land rises (Low Pressure), cool air over water falls (High Pressure). Winds move from the water (High Pressure) to the land (Low Pressure).

Sea Breeze (Morning) Land heats up faster than water. Hot air over land rises (Low Pressure), cool air over water falls (High Pressure). Winds move from the water (High Pressure) to the land (Low Pressure).

Land Breeze (Evening) Land cools off faster than water. Cool air over land falls (High Pressure), warm air over water rises (Low Pressure). Winds move from the land (High Pressure) to the water (Low Pressure).

Land Breeze (Evening) Land cools off faster than water. Cool air over land falls (High Pressure), warm air over water rises (Low Pressure). Winds move from the land (High Pressure) to the water (Low Pressure).

Valley Breeze (Day) During the day the sun warms the air slopes, starting with the top.   Cooler air moves from valley to replace warmer air, creating a breeze.

Mountain Breeze (Night) Air near the top gets cool and sinks, replacing the warm air in the valley.   This cool air moves down the slopes into the valley, producing a mountain breeze!

Global Winds Created by unequal heating of Earth’s surface which causes air to move between the equator and the poles. (equator gets more heat than the poles). Air wants to move from high to low pressure. Warm air (less dense) rises at the equator and cold air (more dense) sinks at the poles..

Global Winds The global wind pattern is also known as the "general circulation" and the surface winds of each hemisphere are divided into three wind belts

Coriolis Effect. As the Earth rotates, winds and currents move in a curved path, called the coriolis effect.

GLOBAL WIND PATTERNS

Global Wind Belts Major global wind systems: Polar easterlies, westerlies, and trade winds.

Global Wind Belts Easterlies: Global (prevailing winds) that blow from the poles, moving from east to west.

Global Wind Belts Westerlies Global winds that move from west to the east in the middle latitudes between 30 and 60 degrees latitude.

Global Wind Belts Trade Winds global winds found near the equator blowing from latitudes 30*N & 30*S.

Jet Streams high speed winds found in Upper troposphere and lower stratosphere Blow from west to east at speeds of 200-400 km/hr. Help airplanes save fuel and time when traveling east.

Doldrums Latitude where the trade winds meet around the equator Very little wind because the warm air rising = low pressure

Horse Latitudes High pressure areas… 300N and 300S Very weak winds

Anemometer- a device used to measure wind speed Anemometer- a device used to measure wind speed. Wind vanes measure wind direction.

Study Jams Video- Air Pressure and Wind http://studyjams. scholastic