There are an estimated 1 billion cows on the planet. A group of cattle in a field. The global cattle inventory is estimated to be about 1 billion.
Today's program is number 26 covering Lesson That's the lesson on wind, dust and deserts, Chapter 19 in the text, and yes, you will note that we are covering Chapter 19 before Chapter 18 getting a little bit out of sequence again in the text.
Deserts are interesting and important geologic features. Not only do they cover about 30 percent of all the land surface on earth,but no other climatic region of any type covers such a large area on the earth. And deserts, like all geological entities, help us to understand the processes and features that have been active in the past; in fact, by understanding these processes and features of deserts today we can help to unravel geologic history, to recognize ancient desert environments, and also understand past climatic changes.
The desert environment is very different from more humid areas and water plays a most significant role even though it's present only in small amounts. So, before we actually start today's lesson, let me remind you of the assignment, that's Chapter 19 in the text, pages It's Lesson 22 in the study guide, and as usual, don't forget to follow the study plan in the study guide, and when you're done,go back to the learning objectives and make sure that you've learned each one.
So, be sure to look at the learning objectives in the study guide before you actually start the lesson. Well, let's take a little overview of the desert. What I'd like to do in today's program is not spend so much time on details but sort of take a little sampler of several of the various features of deserts to see if we can't help to understand the environment.
First of all, what exactly is a desert? All of us, I think, have a sense of what we mean by the desert, but geologically speaking, a desert is simply any region where the precipitation is less than 10 inches per year. This is about 25 centimeters per year. One of the things about deserts is that a small amount of rainfall is usually unreliable, so averages are misleading.
That means that whereas in some places the rainfall may come in pretty continuous amounts, in the desert the rain is usually episodic and often torrential, with long dry periods in between.
That's why one of the reasons we associate the desert with dryness, and, in fact, in some deserts, in Peru, for example, there are regions where no rainfall has ever been recorded in the desert at all. Another characteristic we usually associate with desert is high temperature,but deserts aren't necessarily hot.
We usually think of deserts as being dry, having dry air, but that's not necessarily true either; in fact, right here on Oahu Waikiki actually qualifies as a desert based on the rainfall alone. It's sort of on the borderline of having the 10 centimeters per year, and there, of course, the air is relatively humid.
We also generally think of deserts as having no vegetation. This is not quite true either; in fact, most deserts do actually have a barren look, but if you look closely you see that the desert actually contains many species of generally salt-tolerant plants.
The plants may have extensive and deep root systems, so that they can tap what little water is available and get down deep to reach the deep water table and generally have small leaves to minimize evaporation from the surface during the times when there isn't any water around.
These plants may look like dried dead sticks most of the year, but during a brief rainfall they turn green and flower and go through an entire life cycle of reproduction in a very short period of time. In Hawaii we have some examples of specialized desert plants, the famous silverswords of Maui and the Big Island, for example, are good examples of specialized endemic species which have adjusted to the desert environment, but what about the geographical distribution of deserts?Topic: changes in critical geographical features.
3) Discuss the factors that contribute in the formation of deserts. ( Words) Goh Cheng Leong, Certificate Human and Physical Geography, Chapter – 7. The North Slope of Alaska's Brooks Range also receives less than mm ( in) of precipitation per year and is often classified as a cold desert.
Other regions of the world have cold deserts, including areas of the Himalayas and other high-altitude areas in other parts of the world. Surface Processes in Deserts. Recall that chemical weathering is responsible for the formation of soils Bedrock commonly occurs at the surface.
Long term desertification is also taking place in other parts of the world. In particular, south of the Sahara desert in Africa, the Sahel, is a semi-arid grass land that has been subject to.
Most of the major deserts of the world lie in areas crossed by the trade winds. The world's largest desert, the Sahara of North Africa, which has experienced temperatures as high as 57° C, is a trade wind desert.
The Sahara of Africa is the world's largest desert. Cattle are responsible for 18% of the greenhouse gases that result in global warming; more than all forms of transport combined. The combustion of fuel to produce fertilizer to grow and process feed, clearing of vegetation for grazing, and processing and transporting of meat account for 9% of carbon dioxide produced.
The number of students in U.S. schools who are labeled gifted and talented is million The case in which the U.S. Supreme Court found that if a state undertakes to provide a benefit to its citizenry, such as public education, it must do so without regard to inalterable characteristics, such .