Gartner released its latest report on the global public-cloud market Thursday, forecasting 18.5% growth in 2013, which means the total market size will reach US$131bn worldwide.

Of all services that may be considered “public cloud”, Infrastructure-as-a-Service (IaaS) is the fastest-growing segment. Including cloud compute, storage and print services, the category is expected to grow 47.3% in 2013, reaching full-year sales of $9bn, the market-research house said.

While IaaS is the fastest-growing portion of the market, the largest portion is cloud advertising. The segment comprised 48% of the total market size in 2012, and Gartner expects businesses to spend a total of $310bn on cloud-based advertising services this year.

Ed Anderson, a Gartner research director, said the trend of increasing adoption of cloud services for production systems and workloads will continue in 2013. “Evidence of this growth is found in the increasing demand for cloud services from end-user organizations, met by an increased supply of cloud services from suppliers,” he said.

Following cloud advertising, the second-largest segment of the market is business processes (28%). The segment is followed by Software-as-as-Service (14.7%), Infrastructure-as-a-Service (5.5%), cloud management and security (2.8%) and Platform-as-a-Service (1%).

North America retained its position as the largest consumer of cloud services, forecasted to spend about 60% of all the cash to be spent on cloud services over the next three years, according to Gartner. It is followed by Western Europe, with 24% of global cloud spending.

While nations of the “Free World” are consuming more cloud services than anyone else now, other regions are spending more on cloud faster. Highest growth rates for cloud services continue to come from countries like India, Indonesia, China, Argentina, Mexico and Brazil.

Anderson warned IT services providers that may turn this trend into a rallying cry for a full-frontal offensive on the “developing” nations' cloud market that strategies that worked for them elsewhere may not necessarily be successful in these emerging markets. “Local economic factors, regulatory issues, the local political climate, the diverse landscape of global and local providers, including non-cloud providers and other country-specific factors ensure a unique marketplace in each country and region,” he said.