Transcript Hot Deserts
Climatic Regions Deserts What do you think of when you think of deserts? _____________________ ________________________ ________________________ _________________________ _______________________________ ______________________ _____________________________ Deserts _______________________ _____________________________ ______________________ __________________________ _________________________ __________________ ________________________ ____________________________ _____________________________ Do you think of… There are two types of deserts… Cold Deserts e.g. Antartica Hot Deserts e.g. Sahara Though the temperature can vary, all deserts are defined by an extreme lack of precipitation, between 100 – 250 mm a year Hot Deserts: Hot and dry Egypt Hot Deserts: Hot and dry Hot deserts are very dry between 0 to 250 mm per year of rainfall Very hot usually up to 30°C every day but temperatures of 50°C have been recorded There is a huge difference between night and day temperatures (up to 40°C of a drop) because there is no cloud to keep the heat in The location of hot deserts 15° & 30° North & South of the Equator Can you name any of these deserts? Famous Deserts Sahara Gobi desert Kalahari desert Arabian desert Australian desert Atacama desert Sonoran (Nevada/Mojave) desert Sahara Location: North Africa Size: 9 million sq km Temperature: Up to 45°C in the day: down to -7 °C at night Rainfall: Less than 100mm per year Facts: In Arabic, Sahara means desert (no need to say Sahara desert!) The biggest desert on Earth – as big as the USA About 1/5 is sand – the rest is rocks and pebbles About 6,000 years ago, it was green and wet with crocs and elephants Atacama Desert Location: South America, Peru, Chile Size: 7 million sq km Temperature: Up to 45°C in the day: down to -7 °C at night Rainfall: Less than 100mm per year Facts: It is officially the driest place on earth – some parts received no rain for 400 years! Gobi Location: Central Asia (China and Mongolia) Size: 1,040,000 sq km Temperature: Hot summers up to 45°C, very cold winters down to -40°C Rainfall: 50-100mm per year Facts: In Mongolian it means “waterless place” It is the coldest hot desert in the world It is mostly rock and stones and very mountainous It is home to Bactrian camels The formation of deserts Deserts form for a number of reasons… ? Rain Shadows As the air rises, it cools and drops all its water in the form of rain After the mountain, the air is dry and therefore there is no rain. This dry area is called a rain shadow. Deserts often form in rain shadows. Inland/Continental Deserts Normally, winds coming from the sea have lots of water which falls as rain on land However, some areas are so far away from the sea that the clouds and so rain do not reach them High Pressure Deserts The sun at the equator heats and dries the air The air rises (hot air balloon) The hot air then cools down and sinks There is little or no evaporation and so no rain (the water cycle) So a desert forms Costal/Cold Current Deserts The air over cold currents of water is cold This cold air does not rise and form clouds This cold dry air gets blown over the coast but does not have enough water to fall as rain A mist can form in the morning Just sand? The sand in the desert is constantly moving The wind is one of the main shapers of the desert, creating lines, cresent and star shapes etc in the sand Erosion in the desert Sand can be blasted against rock by the wind forming unusual shapes of rocks When it does rain, a huge amount of water falls very quickly. This causes flash flood that can cause huge damage Conclusion What have you learned today? Did anything surprise you? Would you like to live in the desert? Why? Summary There are two types of deserts – cold and hot Hot deserts are very hot and dry There are many deserts around the world - can you name any? Deserts are formed in a number of ways - van you name them? Homework Name the deserts on the handout Read page 81-86 Looking at the position of the Sahara desert, suggest a reason why it might have formed here. Explain in as much detail as possible.