Complete the following terms: (fill in the blanks with the words below) Waves… Coarse Sand… Feldspar… Trough… Wind… Shoreface
Sediment… Swells…. Quartz… Crest… Wavelength…
The difference between two wave crests (highest point) is called a .

heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.

it is very hard for the climatologists to precisely predict how will the global temperatures be changing so there's lots of models, some of which differ significantly, this is due to multiple factors, and probably the most important is the human activity.

humans have been a key factor in climate change around the globe since the start of the industrial revolution, and in the past few decades the consequences are becoming more obvious. there's lots of emission of pollutants in the atmosphere as well as changing the environment on the surface itself, so it's really hard to predict how will that go in the future because there's some countries that are reducing the damage and are going towards green energy, while others are stubbornly continuing with pollution and damages to the environment.

the rub-al-khali is also known as the arabian desert and the "empty quarter"